1 //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file is a part of AddressSanitizer, an address sanity checker. 11 // Details of the algorithm: 12 // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm 13 // 14 //===----------------------------------------------------------------------===// 15 16 #include "llvm/Transforms/Instrumentation.h" 17 #include "llvm/ADT/ArrayRef.h" 18 #include "llvm/ADT/DenseMap.h" 19 #include "llvm/ADT/DenseSet.h" 20 #include "llvm/ADT/DepthFirstIterator.h" 21 #include "llvm/ADT/SetVector.h" 22 #include "llvm/ADT/SmallSet.h" 23 #include "llvm/ADT/SmallString.h" 24 #include "llvm/ADT/SmallVector.h" 25 #include "llvm/ADT/Statistic.h" 26 #include "llvm/ADT/StringExtras.h" 27 #include "llvm/ADT/Triple.h" 28 #include "llvm/Analysis/MemoryBuiltins.h" 29 #include "llvm/Analysis/TargetLibraryInfo.h" 30 #include "llvm/Analysis/ValueTracking.h" 31 #include "llvm/IR/CallSite.h" 32 #include "llvm/IR/DIBuilder.h" 33 #include "llvm/IR/DataLayout.h" 34 #include "llvm/IR/Dominators.h" 35 #include "llvm/IR/Function.h" 36 #include "llvm/IR/IRBuilder.h" 37 #include "llvm/IR/InlineAsm.h" 38 #include "llvm/IR/InstVisitor.h" 39 #include "llvm/IR/IntrinsicInst.h" 40 #include "llvm/IR/LLVMContext.h" 41 #include "llvm/IR/MDBuilder.h" 42 #include "llvm/IR/Module.h" 43 #include "llvm/IR/Type.h" 44 #include "llvm/MC/MCSectionMachO.h" 45 #include "llvm/Support/CommandLine.h" 46 #include "llvm/Support/DataTypes.h" 47 #include "llvm/Support/Debug.h" 48 #include "llvm/Support/Endian.h" 49 #include "llvm/Support/SwapByteOrder.h" 50 #include "llvm/Support/raw_ostream.h" 51 #include "llvm/Transforms/Scalar.h" 52 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h" 53 #include "llvm/Transforms/Utils/BasicBlockUtils.h" 54 #include "llvm/Transforms/Utils/Cloning.h" 55 #include "llvm/Transforms/Utils/Local.h" 56 #include "llvm/Transforms/Utils/ModuleUtils.h" 57 #include "llvm/Transforms/Utils/PromoteMemToReg.h" 58 #include <algorithm> 59 #include <string> 60 #include <system_error> 61 62 using namespace llvm; 63 64 #define DEBUG_TYPE "asan" 65 66 static const uint64_t kDefaultShadowScale = 3; 67 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29; 68 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44; 69 static const uint64_t kIOSShadowOffset32 = 1ULL << 30; 70 static const uint64_t kIOSShadowOffset64 = 0x120200000; 71 static const uint64_t kIOSSimShadowOffset32 = 1ULL << 30; 72 static const uint64_t kIOSSimShadowOffset64 = kDefaultShadowOffset64; 73 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G. 74 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000; 75 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41; 76 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000; 77 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37; 78 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36; 79 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30; 80 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46; 81 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28; 82 83 static const size_t kMinStackMallocSize = 1 << 6; // 64B 84 static const size_t kMaxStackMallocSize = 1 << 16; // 64K 85 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3; 86 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E; 87 88 static const char *const kAsanModuleCtorName = "asan.module_ctor"; 89 static const char *const kAsanModuleDtorName = "asan.module_dtor"; 90 static const uint64_t kAsanCtorAndDtorPriority = 1; 91 static const char *const kAsanReportErrorTemplate = "__asan_report_"; 92 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals"; 93 static const char *const kAsanUnregisterGlobalsName = 94 "__asan_unregister_globals"; 95 static const char *const kAsanRegisterImageGlobalsName = 96 "__asan_register_image_globals"; 97 static const char *const kAsanUnregisterImageGlobalsName = 98 "__asan_unregister_image_globals"; 99 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init"; 100 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init"; 101 static const char *const kAsanInitName = "__asan_init"; 102 static const char *const kAsanVersionCheckName = 103 "__asan_version_mismatch_check_v8"; 104 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp"; 105 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub"; 106 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return"; 107 static const int kMaxAsanStackMallocSizeClass = 10; 108 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_"; 109 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_"; 110 static const char *const kAsanGenPrefix = "__asan_gen_"; 111 static const char *const kODRGenPrefix = "__odr_asan_gen_"; 112 static const char *const kSanCovGenPrefix = "__sancov_gen_"; 113 static const char *const kAsanPoisonStackMemoryName = 114 "__asan_poison_stack_memory"; 115 static const char *const kAsanUnpoisonStackMemoryName = 116 "__asan_unpoison_stack_memory"; 117 static const char *const kAsanGlobalsRegisteredFlagName = 118 "__asan_globals_registered"; 119 120 static const char *const kAsanOptionDetectUAR = 121 "__asan_option_detect_stack_use_after_return"; 122 123 static const char *const kAsanAllocaPoison = "__asan_alloca_poison"; 124 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison"; 125 126 // Accesses sizes are powers of two: 1, 2, 4, 8, 16. 127 static const size_t kNumberOfAccessSizes = 5; 128 129 static const unsigned kAllocaRzSize = 32; 130 131 // Command-line flags. 132 static cl::opt<bool> ClEnableKasan( 133 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"), 134 cl::Hidden, cl::init(false)); 135 static cl::opt<bool> ClRecover( 136 "asan-recover", 137 cl::desc("Enable recovery mode (continue-after-error)."), 138 cl::Hidden, cl::init(false)); 139 140 // This flag may need to be replaced with -f[no-]asan-reads. 141 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads", 142 cl::desc("instrument read instructions"), 143 cl::Hidden, cl::init(true)); 144 static cl::opt<bool> ClInstrumentWrites( 145 "asan-instrument-writes", cl::desc("instrument write instructions"), 146 cl::Hidden, cl::init(true)); 147 static cl::opt<bool> ClInstrumentAtomics( 148 "asan-instrument-atomics", 149 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden, 150 cl::init(true)); 151 static cl::opt<bool> ClAlwaysSlowPath( 152 "asan-always-slow-path", 153 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden, 154 cl::init(false)); 155 // This flag limits the number of instructions to be instrumented 156 // in any given BB. Normally, this should be set to unlimited (INT_MAX), 157 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary 158 // set it to 10000. 159 static cl::opt<int> ClMaxInsnsToInstrumentPerBB( 160 "asan-max-ins-per-bb", cl::init(10000), 161 cl::desc("maximal number of instructions to instrument in any given BB"), 162 cl::Hidden); 163 // This flag may need to be replaced with -f[no]asan-stack. 164 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"), 165 cl::Hidden, cl::init(true)); 166 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return", 167 cl::desc("Check return-after-free"), 168 cl::Hidden, cl::init(true)); 169 // This flag may need to be replaced with -f[no]asan-globals. 170 static cl::opt<bool> ClGlobals("asan-globals", 171 cl::desc("Handle global objects"), cl::Hidden, 172 cl::init(true)); 173 static cl::opt<bool> ClInitializers("asan-initialization-order", 174 cl::desc("Handle C++ initializer order"), 175 cl::Hidden, cl::init(true)); 176 static cl::opt<bool> ClInvalidPointerPairs( 177 "asan-detect-invalid-pointer-pair", 178 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden, 179 cl::init(false)); 180 static cl::opt<unsigned> ClRealignStack( 181 "asan-realign-stack", 182 cl::desc("Realign stack to the value of this flag (power of two)"), 183 cl::Hidden, cl::init(32)); 184 static cl::opt<int> ClInstrumentationWithCallsThreshold( 185 "asan-instrumentation-with-call-threshold", 186 cl::desc( 187 "If the function being instrumented contains more than " 188 "this number of memory accesses, use callbacks instead of " 189 "inline checks (-1 means never use callbacks)."), 190 cl::Hidden, cl::init(7000)); 191 static cl::opt<std::string> ClMemoryAccessCallbackPrefix( 192 "asan-memory-access-callback-prefix", 193 cl::desc("Prefix for memory access callbacks"), cl::Hidden, 194 cl::init("__asan_")); 195 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas", 196 cl::desc("instrument dynamic allocas"), 197 cl::Hidden, cl::init(true)); 198 static cl::opt<bool> ClSkipPromotableAllocas( 199 "asan-skip-promotable-allocas", 200 cl::desc("Do not instrument promotable allocas"), cl::Hidden, 201 cl::init(true)); 202 203 // These flags allow to change the shadow mapping. 204 // The shadow mapping looks like 205 // Shadow = (Mem >> scale) + (1 << offset_log) 206 static cl::opt<int> ClMappingScale("asan-mapping-scale", 207 cl::desc("scale of asan shadow mapping"), 208 cl::Hidden, cl::init(0)); 209 210 // Optimization flags. Not user visible, used mostly for testing 211 // and benchmarking the tool. 212 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"), 213 cl::Hidden, cl::init(true)); 214 static cl::opt<bool> ClOptSameTemp( 215 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"), 216 cl::Hidden, cl::init(true)); 217 static cl::opt<bool> ClOptGlobals("asan-opt-globals", 218 cl::desc("Don't instrument scalar globals"), 219 cl::Hidden, cl::init(true)); 220 static cl::opt<bool> ClOptStack( 221 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"), 222 cl::Hidden, cl::init(false)); 223 224 static cl::opt<bool> ClCheckLifetime( 225 "asan-check-lifetime", 226 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), cl::Hidden, 227 cl::init(false)); 228 229 static cl::opt<bool> ClDynamicAllocaStack( 230 "asan-stack-dynamic-alloca", 231 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden, 232 cl::init(true)); 233 234 static cl::opt<uint32_t> ClForceExperiment( 235 "asan-force-experiment", 236 cl::desc("Force optimization experiment (for testing)"), cl::Hidden, 237 cl::init(0)); 238 239 static cl::opt<bool> 240 ClUsePrivateAliasForGlobals("asan-use-private-alias", 241 cl::desc("Use private aliases for global" 242 " variables"), 243 cl::Hidden, cl::init(false)); 244 245 // Debug flags. 246 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden, 247 cl::init(0)); 248 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"), 249 cl::Hidden, cl::init(0)); 250 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden, 251 cl::desc("Debug func")); 252 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"), 253 cl::Hidden, cl::init(-1)); 254 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"), 255 cl::Hidden, cl::init(-1)); 256 257 STATISTIC(NumInstrumentedReads, "Number of instrumented reads"); 258 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes"); 259 STATISTIC(NumOptimizedAccessesToGlobalVar, 260 "Number of optimized accesses to global vars"); 261 STATISTIC(NumOptimizedAccessesToStackVar, 262 "Number of optimized accesses to stack vars"); 263 264 namespace { 265 /// Frontend-provided metadata for source location. 266 struct LocationMetadata { 267 StringRef Filename; 268 int LineNo; 269 int ColumnNo; 270 271 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {} 272 273 bool empty() const { return Filename.empty(); } 274 275 void parse(MDNode *MDN) { 276 assert(MDN->getNumOperands() == 3); 277 MDString *DIFilename = cast<MDString>(MDN->getOperand(0)); 278 Filename = DIFilename->getString(); 279 LineNo = 280 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue(); 281 ColumnNo = 282 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue(); 283 } 284 }; 285 286 /// Frontend-provided metadata for global variables. 287 class GlobalsMetadata { 288 public: 289 struct Entry { 290 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {} 291 LocationMetadata SourceLoc; 292 StringRef Name; 293 bool IsDynInit; 294 bool IsBlacklisted; 295 }; 296 297 GlobalsMetadata() : inited_(false) {} 298 299 void reset() { 300 inited_ = false; 301 Entries.clear(); 302 } 303 304 void init(Module &M) { 305 assert(!inited_); 306 inited_ = true; 307 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals"); 308 if (!Globals) return; 309 for (auto MDN : Globals->operands()) { 310 // Metadata node contains the global and the fields of "Entry". 311 assert(MDN->getNumOperands() == 5); 312 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0)); 313 // The optimizer may optimize away a global entirely. 314 if (!GV) continue; 315 // We can already have an entry for GV if it was merged with another 316 // global. 317 Entry &E = Entries[GV]; 318 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1))) 319 E.SourceLoc.parse(Loc); 320 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2))) 321 E.Name = Name->getString(); 322 ConstantInt *IsDynInit = 323 mdconst::extract<ConstantInt>(MDN->getOperand(3)); 324 E.IsDynInit |= IsDynInit->isOne(); 325 ConstantInt *IsBlacklisted = 326 mdconst::extract<ConstantInt>(MDN->getOperand(4)); 327 E.IsBlacklisted |= IsBlacklisted->isOne(); 328 } 329 } 330 331 /// Returns metadata entry for a given global. 332 Entry get(GlobalVariable *G) const { 333 auto Pos = Entries.find(G); 334 return (Pos != Entries.end()) ? Pos->second : Entry(); 335 } 336 337 private: 338 bool inited_; 339 DenseMap<GlobalVariable *, Entry> Entries; 340 }; 341 342 /// This struct defines the shadow mapping using the rule: 343 /// shadow = (mem >> Scale) ADD-or-OR Offset. 344 struct ShadowMapping { 345 int Scale; 346 uint64_t Offset; 347 bool OrShadowOffset; 348 }; 349 350 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize, 351 bool IsKasan) { 352 bool IsAndroid = TargetTriple.isAndroid(); 353 bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS(); 354 bool IsFreeBSD = TargetTriple.isOSFreeBSD(); 355 bool IsLinux = TargetTriple.isOSLinux(); 356 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 || 357 TargetTriple.getArch() == llvm::Triple::ppc64le; 358 bool IsX86 = TargetTriple.getArch() == llvm::Triple::x86; 359 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64; 360 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips || 361 TargetTriple.getArch() == llvm::Triple::mipsel; 362 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 || 363 TargetTriple.getArch() == llvm::Triple::mips64el; 364 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64; 365 bool IsWindows = TargetTriple.isOSWindows(); 366 367 ShadowMapping Mapping; 368 369 if (LongSize == 32) { 370 // Android is always PIE, which means that the beginning of the address 371 // space is always available. 372 if (IsAndroid) 373 Mapping.Offset = 0; 374 else if (IsMIPS32) 375 Mapping.Offset = kMIPS32_ShadowOffset32; 376 else if (IsFreeBSD) 377 Mapping.Offset = kFreeBSD_ShadowOffset32; 378 else if (IsIOS) 379 // If we're targeting iOS and x86, the binary is built for iOS simulator. 380 Mapping.Offset = IsX86 ? kIOSSimShadowOffset32 : kIOSShadowOffset32; 381 else if (IsWindows) 382 Mapping.Offset = kWindowsShadowOffset32; 383 else 384 Mapping.Offset = kDefaultShadowOffset32; 385 } else { // LongSize == 64 386 if (IsPPC64) 387 Mapping.Offset = kPPC64_ShadowOffset64; 388 else if (IsFreeBSD) 389 Mapping.Offset = kFreeBSD_ShadowOffset64; 390 else if (IsLinux && IsX86_64) { 391 if (IsKasan) 392 Mapping.Offset = kLinuxKasan_ShadowOffset64; 393 else 394 Mapping.Offset = kSmallX86_64ShadowOffset; 395 } else if (IsMIPS64) 396 Mapping.Offset = kMIPS64_ShadowOffset64; 397 else if (IsIOS) 398 // If we're targeting iOS and x86, the binary is built for iOS simulator. 399 Mapping.Offset = IsX86_64 ? kIOSSimShadowOffset64 : kIOSShadowOffset64; 400 else if (IsAArch64) 401 Mapping.Offset = kAArch64_ShadowOffset64; 402 else 403 Mapping.Offset = kDefaultShadowOffset64; 404 } 405 406 Mapping.Scale = kDefaultShadowScale; 407 if (ClMappingScale) { 408 Mapping.Scale = ClMappingScale; 409 } 410 411 // OR-ing shadow offset if more efficient (at least on x86) if the offset 412 // is a power of two, but on ppc64 we have to use add since the shadow 413 // offset is not necessary 1/8-th of the address space. 414 Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64 415 && !(Mapping.Offset & (Mapping.Offset - 1)); 416 417 return Mapping; 418 } 419 420 static size_t RedzoneSizeForScale(int MappingScale) { 421 // Redzone used for stack and globals is at least 32 bytes. 422 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively. 423 return std::max(32U, 1U << MappingScale); 424 } 425 426 /// AddressSanitizer: instrument the code in module to find memory bugs. 427 struct AddressSanitizer : public FunctionPass { 428 explicit AddressSanitizer(bool CompileKernel = false, bool Recover = false) 429 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan), 430 Recover(Recover || ClRecover) { 431 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry()); 432 } 433 const char *getPassName() const override { 434 return "AddressSanitizerFunctionPass"; 435 } 436 void getAnalysisUsage(AnalysisUsage &AU) const override { 437 AU.addRequired<DominatorTreeWrapperPass>(); 438 AU.addRequired<TargetLibraryInfoWrapperPass>(); 439 } 440 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const { 441 Type *Ty = AI->getAllocatedType(); 442 uint64_t SizeInBytes = 443 AI->getModule()->getDataLayout().getTypeAllocSize(Ty); 444 return SizeInBytes; 445 } 446 /// Check if we want (and can) handle this alloca. 447 bool isInterestingAlloca(AllocaInst &AI); 448 449 // Check if we have dynamic alloca. 450 bool isDynamicAlloca(AllocaInst &AI) const { 451 return AI.isArrayAllocation() || !AI.isStaticAlloca(); 452 } 453 454 /// If it is an interesting memory access, return the PointerOperand 455 /// and set IsWrite/Alignment. Otherwise return nullptr. 456 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite, 457 uint64_t *TypeSize, unsigned *Alignment); 458 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I, 459 bool UseCalls, const DataLayout &DL); 460 void instrumentPointerComparisonOrSubtraction(Instruction *I); 461 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore, 462 Value *Addr, uint32_t TypeSize, bool IsWrite, 463 Value *SizeArgument, bool UseCalls, uint32_t Exp); 464 void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr, 465 uint32_t TypeSize, bool IsWrite, 466 Value *SizeArgument, bool UseCalls, 467 uint32_t Exp); 468 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong, 469 Value *ShadowValue, uint32_t TypeSize); 470 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr, 471 bool IsWrite, size_t AccessSizeIndex, 472 Value *SizeArgument, uint32_t Exp); 473 void instrumentMemIntrinsic(MemIntrinsic *MI); 474 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB); 475 bool runOnFunction(Function &F) override; 476 bool maybeInsertAsanInitAtFunctionEntry(Function &F); 477 void markEscapedLocalAllocas(Function &F); 478 bool doInitialization(Module &M) override; 479 bool doFinalization(Module &M) override; 480 static char ID; // Pass identification, replacement for typeid 481 482 DominatorTree &getDominatorTree() const { return *DT; } 483 484 private: 485 void initializeCallbacks(Module &M); 486 487 bool LooksLikeCodeInBug11395(Instruction *I); 488 bool GlobalIsLinkerInitialized(GlobalVariable *G); 489 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr, 490 uint64_t TypeSize) const; 491 492 /// Helper to cleanup per-function state. 493 struct FunctionStateRAII { 494 AddressSanitizer *Pass; 495 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) { 496 assert(Pass->ProcessedAllocas.empty() && 497 "last pass forgot to clear cache"); 498 } 499 ~FunctionStateRAII() { Pass->ProcessedAllocas.clear(); } 500 }; 501 502 LLVMContext *C; 503 Triple TargetTriple; 504 int LongSize; 505 bool CompileKernel; 506 bool Recover; 507 Type *IntptrTy; 508 ShadowMapping Mapping; 509 DominatorTree *DT; 510 Function *AsanCtorFunction = nullptr; 511 Function *AsanInitFunction = nullptr; 512 Function *AsanHandleNoReturnFunc; 513 Function *AsanPtrCmpFunction, *AsanPtrSubFunction; 514 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize). 515 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes]; 516 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes]; 517 // This array is indexed by AccessIsWrite and Experiment. 518 Function *AsanErrorCallbackSized[2][2]; 519 Function *AsanMemoryAccessCallbackSized[2][2]; 520 Function *AsanMemmove, *AsanMemcpy, *AsanMemset; 521 InlineAsm *EmptyAsm; 522 GlobalsMetadata GlobalsMD; 523 DenseMap<AllocaInst *, bool> ProcessedAllocas; 524 525 friend struct FunctionStackPoisoner; 526 }; 527 528 class AddressSanitizerModule : public ModulePass { 529 public: 530 explicit AddressSanitizerModule(bool CompileKernel = false, 531 bool Recover = false) 532 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan), 533 Recover(Recover || ClRecover) {} 534 bool runOnModule(Module &M) override; 535 static char ID; // Pass identification, replacement for typeid 536 const char *getPassName() const override { return "AddressSanitizerModule"; } 537 538 private: 539 void initializeCallbacks(Module &M); 540 541 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M); 542 bool ShouldInstrumentGlobal(GlobalVariable *G); 543 bool ShouldUseMachOGlobalsSection() const; 544 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName); 545 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName); 546 size_t MinRedzoneSizeForGlobal() const { 547 return RedzoneSizeForScale(Mapping.Scale); 548 } 549 550 GlobalsMetadata GlobalsMD; 551 bool CompileKernel; 552 bool Recover; 553 Type *IntptrTy; 554 LLVMContext *C; 555 Triple TargetTriple; 556 ShadowMapping Mapping; 557 Function *AsanPoisonGlobals; 558 Function *AsanUnpoisonGlobals; 559 Function *AsanRegisterGlobals; 560 Function *AsanUnregisterGlobals; 561 Function *AsanRegisterImageGlobals; 562 Function *AsanUnregisterImageGlobals; 563 }; 564 565 // Stack poisoning does not play well with exception handling. 566 // When an exception is thrown, we essentially bypass the code 567 // that unpoisones the stack. This is why the run-time library has 568 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire 569 // stack in the interceptor. This however does not work inside the 570 // actual function which catches the exception. Most likely because the 571 // compiler hoists the load of the shadow value somewhere too high. 572 // This causes asan to report a non-existing bug on 453.povray. 573 // It sounds like an LLVM bug. 574 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> { 575 Function &F; 576 AddressSanitizer &ASan; 577 DIBuilder DIB; 578 LLVMContext *C; 579 Type *IntptrTy; 580 Type *IntptrPtrTy; 581 ShadowMapping Mapping; 582 583 SmallVector<AllocaInst *, 16> AllocaVec; 584 SmallSetVector<AllocaInst *, 16> NonInstrumentedStaticAllocaVec; 585 SmallVector<Instruction *, 8> RetVec; 586 unsigned StackAlignment; 587 588 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1], 589 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1]; 590 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc; 591 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc; 592 593 // Stores a place and arguments of poisoning/unpoisoning call for alloca. 594 struct AllocaPoisonCall { 595 IntrinsicInst *InsBefore; 596 AllocaInst *AI; 597 uint64_t Size; 598 bool DoPoison; 599 }; 600 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec; 601 602 SmallVector<AllocaInst *, 1> DynamicAllocaVec; 603 SmallVector<IntrinsicInst *, 1> StackRestoreVec; 604 AllocaInst *DynamicAllocaLayout = nullptr; 605 IntrinsicInst *LocalEscapeCall = nullptr; 606 607 // Maps Value to an AllocaInst from which the Value is originated. 608 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy; 609 AllocaForValueMapTy AllocaForValue; 610 611 bool HasNonEmptyInlineAsm = false; 612 bool HasReturnsTwiceCall = false; 613 std::unique_ptr<CallInst> EmptyInlineAsm; 614 615 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan) 616 : F(F), 617 ASan(ASan), 618 DIB(*F.getParent(), /*AllowUnresolved*/ false), 619 C(ASan.C), 620 IntptrTy(ASan.IntptrTy), 621 IntptrPtrTy(PointerType::get(IntptrTy, 0)), 622 Mapping(ASan.Mapping), 623 StackAlignment(1 << Mapping.Scale), 624 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {} 625 626 bool runOnFunction() { 627 if (!ClStack) return false; 628 // Collect alloca, ret, lifetime instructions etc. 629 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB); 630 631 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false; 632 633 initializeCallbacks(*F.getParent()); 634 635 poisonStack(); 636 637 if (ClDebugStack) { 638 DEBUG(dbgs() << F); 639 } 640 return true; 641 } 642 643 // Finds all Alloca instructions and puts 644 // poisoned red zones around all of them. 645 // Then unpoison everything back before the function returns. 646 void poisonStack(); 647 648 void createDynamicAllocasInitStorage(); 649 650 // ----------------------- Visitors. 651 /// \brief Collect all Ret instructions. 652 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); } 653 654 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore, 655 Value *SavedStack) { 656 IRBuilder<> IRB(InstBefore); 657 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy); 658 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we 659 // need to adjust extracted SP to compute the address of the most recent 660 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for 661 // this purpose. 662 if (!isa<ReturnInst>(InstBefore)) { 663 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration( 664 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset, 665 {IntptrTy}); 666 667 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {}); 668 669 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy), 670 DynamicAreaOffset); 671 } 672 673 IRB.CreateCall(AsanAllocasUnpoisonFunc, 674 {IRB.CreateLoad(DynamicAllocaLayout), DynamicAreaPtr}); 675 } 676 677 // Unpoison dynamic allocas redzones. 678 void unpoisonDynamicAllocas() { 679 for (auto &Ret : RetVec) 680 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout); 681 682 for (auto &StackRestoreInst : StackRestoreVec) 683 unpoisonDynamicAllocasBeforeInst(StackRestoreInst, 684 StackRestoreInst->getOperand(0)); 685 } 686 687 // Deploy and poison redzones around dynamic alloca call. To do this, we 688 // should replace this call with another one with changed parameters and 689 // replace all its uses with new address, so 690 // addr = alloca type, old_size, align 691 // is replaced by 692 // new_size = (old_size + additional_size) * sizeof(type) 693 // tmp = alloca i8, new_size, max(align, 32) 694 // addr = tmp + 32 (first 32 bytes are for the left redzone). 695 // Additional_size is added to make new memory allocation contain not only 696 // requested memory, but also left, partial and right redzones. 697 void handleDynamicAllocaCall(AllocaInst *AI); 698 699 /// \brief Collect Alloca instructions we want (and can) handle. 700 void visitAllocaInst(AllocaInst &AI) { 701 if (!ASan.isInterestingAlloca(AI)) { 702 if (AI.isStaticAlloca()) NonInstrumentedStaticAllocaVec.insert(&AI); 703 return; 704 } 705 706 StackAlignment = std::max(StackAlignment, AI.getAlignment()); 707 if (ASan.isDynamicAlloca(AI)) 708 DynamicAllocaVec.push_back(&AI); 709 else 710 AllocaVec.push_back(&AI); 711 } 712 713 /// \brief Collect lifetime intrinsic calls to check for use-after-scope 714 /// errors. 715 void visitIntrinsicInst(IntrinsicInst &II) { 716 Intrinsic::ID ID = II.getIntrinsicID(); 717 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II); 718 if (ID == Intrinsic::localescape) LocalEscapeCall = &II; 719 if (!ClCheckLifetime) return; 720 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end) 721 return; 722 // Found lifetime intrinsic, add ASan instrumentation if necessary. 723 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0)); 724 // If size argument is undefined, don't do anything. 725 if (Size->isMinusOne()) return; 726 // Check that size doesn't saturate uint64_t and can 727 // be stored in IntptrTy. 728 const uint64_t SizeValue = Size->getValue().getLimitedValue(); 729 if (SizeValue == ~0ULL || 730 !ConstantInt::isValueValidForType(IntptrTy, SizeValue)) 731 return; 732 // Find alloca instruction that corresponds to llvm.lifetime argument. 733 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1)); 734 if (!AI) return; 735 bool DoPoison = (ID == Intrinsic::lifetime_end); 736 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison}; 737 AllocaPoisonCallVec.push_back(APC); 738 } 739 740 void visitCallSite(CallSite CS) { 741 Instruction *I = CS.getInstruction(); 742 if (CallInst *CI = dyn_cast<CallInst>(I)) { 743 HasNonEmptyInlineAsm |= 744 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get()); 745 HasReturnsTwiceCall |= CI->canReturnTwice(); 746 } 747 } 748 749 // ---------------------- Helpers. 750 void initializeCallbacks(Module &M); 751 752 bool doesDominateAllExits(const Instruction *I) const { 753 for (auto Ret : RetVec) { 754 if (!ASan.getDominatorTree().dominates(I, Ret)) return false; 755 } 756 return true; 757 } 758 759 /// Finds alloca where the value comes from. 760 AllocaInst *findAllocaForValue(Value *V); 761 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB, 762 Value *ShadowBase, bool DoPoison); 763 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison); 764 765 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase, 766 int Size); 767 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L, 768 bool Dynamic); 769 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue, 770 Instruction *ThenTerm, Value *ValueIfFalse); 771 }; 772 773 } // anonymous namespace 774 775 char AddressSanitizer::ID = 0; 776 INITIALIZE_PASS_BEGIN( 777 AddressSanitizer, "asan", 778 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false, 779 false) 780 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) 781 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass) 782 INITIALIZE_PASS_END( 783 AddressSanitizer, "asan", 784 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false, 785 false) 786 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel, 787 bool Recover) { 788 assert(!CompileKernel || Recover); 789 return new AddressSanitizer(CompileKernel, Recover); 790 } 791 792 char AddressSanitizerModule::ID = 0; 793 INITIALIZE_PASS( 794 AddressSanitizerModule, "asan-module", 795 "AddressSanitizer: detects use-after-free and out-of-bounds bugs." 796 "ModulePass", 797 false, false) 798 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel, 799 bool Recover) { 800 assert(!CompileKernel || Recover); 801 return new AddressSanitizerModule(CompileKernel, Recover); 802 } 803 804 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) { 805 size_t Res = countTrailingZeros(TypeSize / 8); 806 assert(Res < kNumberOfAccessSizes); 807 return Res; 808 } 809 810 // \brief Create a constant for Str so that we can pass it to the run-time lib. 811 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str, 812 bool AllowMerging) { 813 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str); 814 // We use private linkage for module-local strings. If they can be merged 815 // with another one, we set the unnamed_addr attribute. 816 GlobalVariable *GV = 817 new GlobalVariable(M, StrConst->getType(), true, 818 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix); 819 if (AllowMerging) GV->setUnnamedAddr(true); 820 GV->setAlignment(1); // Strings may not be merged w/o setting align 1. 821 return GV; 822 } 823 824 /// \brief Create a global describing a source location. 825 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M, 826 LocationMetadata MD) { 827 Constant *LocData[] = { 828 createPrivateGlobalForString(M, MD.Filename, true), 829 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo), 830 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo), 831 }; 832 auto LocStruct = ConstantStruct::getAnon(LocData); 833 auto GV = new GlobalVariable(M, LocStruct->getType(), true, 834 GlobalValue::PrivateLinkage, LocStruct, 835 kAsanGenPrefix); 836 GV->setUnnamedAddr(true); 837 return GV; 838 } 839 840 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) { 841 return G->getName().find(kAsanGenPrefix) == 0 || 842 G->getName().find(kSanCovGenPrefix) == 0 || 843 G->getName().find(kODRGenPrefix) == 0; 844 } 845 846 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) { 847 // Shadow >> scale 848 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale); 849 if (Mapping.Offset == 0) return Shadow; 850 // (Shadow >> scale) | offset 851 if (Mapping.OrShadowOffset) 852 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset)); 853 else 854 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset)); 855 } 856 857 // Instrument memset/memmove/memcpy 858 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) { 859 IRBuilder<> IRB(MI); 860 if (isa<MemTransferInst>(MI)) { 861 IRB.CreateCall( 862 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy, 863 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()), 864 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()), 865 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)}); 866 } else if (isa<MemSetInst>(MI)) { 867 IRB.CreateCall( 868 AsanMemset, 869 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()), 870 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false), 871 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)}); 872 } 873 MI->eraseFromParent(); 874 } 875 876 /// Check if we want (and can) handle this alloca. 877 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) { 878 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI); 879 880 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end()) 881 return PreviouslySeenAllocaInfo->getSecond(); 882 883 bool IsInteresting = 884 (AI.getAllocatedType()->isSized() && 885 // alloca() may be called with 0 size, ignore it. 886 getAllocaSizeInBytes(&AI) > 0 && 887 // We are only interested in allocas not promotable to registers. 888 // Promotable allocas are common under -O0. 889 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) && 890 // inalloca allocas are not treated as static, and we don't want 891 // dynamic alloca instrumentation for them as well. 892 !AI.isUsedWithInAlloca()); 893 894 ProcessedAllocas[&AI] = IsInteresting; 895 return IsInteresting; 896 } 897 898 /// If I is an interesting memory access, return the PointerOperand 899 /// and set IsWrite/Alignment. Otherwise return nullptr. 900 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I, 901 bool *IsWrite, 902 uint64_t *TypeSize, 903 unsigned *Alignment) { 904 // Skip memory accesses inserted by another instrumentation. 905 if (I->getMetadata("nosanitize")) return nullptr; 906 907 Value *PtrOperand = nullptr; 908 const DataLayout &DL = I->getModule()->getDataLayout(); 909 if (LoadInst *LI = dyn_cast<LoadInst>(I)) { 910 if (!ClInstrumentReads) return nullptr; 911 *IsWrite = false; 912 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType()); 913 *Alignment = LI->getAlignment(); 914 PtrOperand = LI->getPointerOperand(); 915 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) { 916 if (!ClInstrumentWrites) return nullptr; 917 *IsWrite = true; 918 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType()); 919 *Alignment = SI->getAlignment(); 920 PtrOperand = SI->getPointerOperand(); 921 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) { 922 if (!ClInstrumentAtomics) return nullptr; 923 *IsWrite = true; 924 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType()); 925 *Alignment = 0; 926 PtrOperand = RMW->getPointerOperand(); 927 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) { 928 if (!ClInstrumentAtomics) return nullptr; 929 *IsWrite = true; 930 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType()); 931 *Alignment = 0; 932 PtrOperand = XCHG->getPointerOperand(); 933 } 934 935 // Treat memory accesses to promotable allocas as non-interesting since they 936 // will not cause memory violations. This greatly speeds up the instrumented 937 // executable at -O0. 938 if (ClSkipPromotableAllocas) 939 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand)) 940 return isInterestingAlloca(*AI) ? AI : nullptr; 941 942 return PtrOperand; 943 } 944 945 static bool isPointerOperand(Value *V) { 946 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V); 947 } 948 949 // This is a rough heuristic; it may cause both false positives and 950 // false negatives. The proper implementation requires cooperation with 951 // the frontend. 952 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) { 953 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) { 954 if (!Cmp->isRelational()) return false; 955 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) { 956 if (BO->getOpcode() != Instruction::Sub) return false; 957 } else { 958 return false; 959 } 960 return isPointerOperand(I->getOperand(0)) && 961 isPointerOperand(I->getOperand(1)); 962 } 963 964 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) { 965 // If a global variable does not have dynamic initialization we don't 966 // have to instrument it. However, if a global does not have initializer 967 // at all, we assume it has dynamic initializer (in other TU). 968 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit; 969 } 970 971 void AddressSanitizer::instrumentPointerComparisonOrSubtraction( 972 Instruction *I) { 973 IRBuilder<> IRB(I); 974 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction; 975 Value *Param[2] = {I->getOperand(0), I->getOperand(1)}; 976 for (int i = 0; i < 2; i++) { 977 if (Param[i]->getType()->isPointerTy()) 978 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy); 979 } 980 IRB.CreateCall(F, Param); 981 } 982 983 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, 984 Instruction *I, bool UseCalls, 985 const DataLayout &DL) { 986 bool IsWrite = false; 987 unsigned Alignment = 0; 988 uint64_t TypeSize = 0; 989 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment); 990 assert(Addr); 991 992 // Optimization experiments. 993 // The experiments can be used to evaluate potential optimizations that remove 994 // instrumentation (assess false negatives). Instead of completely removing 995 // some instrumentation, you set Exp to a non-zero value (mask of optimization 996 // experiments that want to remove instrumentation of this instruction). 997 // If Exp is non-zero, this pass will emit special calls into runtime 998 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls 999 // make runtime terminate the program in a special way (with a different 1000 // exit status). Then you run the new compiler on a buggy corpus, collect 1001 // the special terminations (ideally, you don't see them at all -- no false 1002 // negatives) and make the decision on the optimization. 1003 uint32_t Exp = ClForceExperiment; 1004 1005 if (ClOpt && ClOptGlobals) { 1006 // If initialization order checking is disabled, a simple access to a 1007 // dynamically initialized global is always valid. 1008 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL)); 1009 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) && 1010 isSafeAccess(ObjSizeVis, Addr, TypeSize)) { 1011 NumOptimizedAccessesToGlobalVar++; 1012 return; 1013 } 1014 } 1015 1016 if (ClOpt && ClOptStack) { 1017 // A direct inbounds access to a stack variable is always valid. 1018 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) && 1019 isSafeAccess(ObjSizeVis, Addr, TypeSize)) { 1020 NumOptimizedAccessesToStackVar++; 1021 return; 1022 } 1023 } 1024 1025 if (IsWrite) 1026 NumInstrumentedWrites++; 1027 else 1028 NumInstrumentedReads++; 1029 1030 unsigned Granularity = 1 << Mapping.Scale; 1031 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check 1032 // if the data is properly aligned. 1033 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 || 1034 TypeSize == 128) && 1035 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8)) 1036 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls, 1037 Exp); 1038 instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr, 1039 UseCalls, Exp); 1040 } 1041 1042 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore, 1043 Value *Addr, bool IsWrite, 1044 size_t AccessSizeIndex, 1045 Value *SizeArgument, 1046 uint32_t Exp) { 1047 IRBuilder<> IRB(InsertBefore); 1048 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp); 1049 CallInst *Call = nullptr; 1050 if (SizeArgument) { 1051 if (Exp == 0) 1052 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0], 1053 {Addr, SizeArgument}); 1054 else 1055 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1], 1056 {Addr, SizeArgument, ExpVal}); 1057 } else { 1058 if (Exp == 0) 1059 Call = 1060 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr); 1061 else 1062 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex], 1063 {Addr, ExpVal}); 1064 } 1065 1066 // We don't do Call->setDoesNotReturn() because the BB already has 1067 // UnreachableInst at the end. 1068 // This EmptyAsm is required to avoid callback merge. 1069 IRB.CreateCall(EmptyAsm, {}); 1070 return Call; 1071 } 1072 1073 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong, 1074 Value *ShadowValue, 1075 uint32_t TypeSize) { 1076 size_t Granularity = static_cast<size_t>(1) << Mapping.Scale; 1077 // Addr & (Granularity - 1) 1078 Value *LastAccessedByte = 1079 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1)); 1080 // (Addr & (Granularity - 1)) + size - 1 1081 if (TypeSize / 8 > 1) 1082 LastAccessedByte = IRB.CreateAdd( 1083 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)); 1084 // (uint8_t) ((Addr & (Granularity-1)) + size - 1) 1085 LastAccessedByte = 1086 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false); 1087 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue 1088 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue); 1089 } 1090 1091 void AddressSanitizer::instrumentAddress(Instruction *OrigIns, 1092 Instruction *InsertBefore, Value *Addr, 1093 uint32_t TypeSize, bool IsWrite, 1094 Value *SizeArgument, bool UseCalls, 1095 uint32_t Exp) { 1096 IRBuilder<> IRB(InsertBefore); 1097 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy); 1098 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize); 1099 1100 if (UseCalls) { 1101 if (Exp == 0) 1102 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex], 1103 AddrLong); 1104 else 1105 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex], 1106 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)}); 1107 return; 1108 } 1109 1110 Type *ShadowTy = 1111 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale)); 1112 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0); 1113 Value *ShadowPtr = memToShadow(AddrLong, IRB); 1114 Value *CmpVal = Constant::getNullValue(ShadowTy); 1115 Value *ShadowValue = 1116 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy)); 1117 1118 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal); 1119 size_t Granularity = 1ULL << Mapping.Scale; 1120 TerminatorInst *CrashTerm = nullptr; 1121 1122 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) { 1123 // We use branch weights for the slow path check, to indicate that the slow 1124 // path is rarely taken. This seems to be the case for SPEC benchmarks. 1125 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen( 1126 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000)); 1127 assert(cast<BranchInst>(CheckTerm)->isUnconditional()); 1128 BasicBlock *NextBB = CheckTerm->getSuccessor(0); 1129 IRB.SetInsertPoint(CheckTerm); 1130 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize); 1131 if (Recover) { 1132 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false); 1133 } else { 1134 BasicBlock *CrashBlock = 1135 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB); 1136 CrashTerm = new UnreachableInst(*C, CrashBlock); 1137 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2); 1138 ReplaceInstWithInst(CheckTerm, NewTerm); 1139 } 1140 } else { 1141 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover); 1142 } 1143 1144 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite, 1145 AccessSizeIndex, SizeArgument, Exp); 1146 Crash->setDebugLoc(OrigIns->getDebugLoc()); 1147 } 1148 1149 // Instrument unusual size or unusual alignment. 1150 // We can not do it with a single check, so we do 1-byte check for the first 1151 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able 1152 // to report the actual access size. 1153 void AddressSanitizer::instrumentUnusualSizeOrAlignment( 1154 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite, 1155 Value *SizeArgument, bool UseCalls, uint32_t Exp) { 1156 IRBuilder<> IRB(I); 1157 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8); 1158 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy); 1159 if (UseCalls) { 1160 if (Exp == 0) 1161 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0], 1162 {AddrLong, Size}); 1163 else 1164 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1], 1165 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)}); 1166 } else { 1167 Value *LastByte = IRB.CreateIntToPtr( 1168 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)), 1169 Addr->getType()); 1170 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp); 1171 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp); 1172 } 1173 } 1174 1175 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit, 1176 GlobalValue *ModuleName) { 1177 // Set up the arguments to our poison/unpoison functions. 1178 IRBuilder<> IRB(&GlobalInit.front(), 1179 GlobalInit.front().getFirstInsertionPt()); 1180 1181 // Add a call to poison all external globals before the given function starts. 1182 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy); 1183 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr); 1184 1185 // Add calls to unpoison all globals before each return instruction. 1186 for (auto &BB : GlobalInit.getBasicBlockList()) 1187 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator())) 1188 CallInst::Create(AsanUnpoisonGlobals, "", RI); 1189 } 1190 1191 void AddressSanitizerModule::createInitializerPoisonCalls( 1192 Module &M, GlobalValue *ModuleName) { 1193 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors"); 1194 1195 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer()); 1196 for (Use &OP : CA->operands()) { 1197 if (isa<ConstantAggregateZero>(OP)) continue; 1198 ConstantStruct *CS = cast<ConstantStruct>(OP); 1199 1200 // Must have a function or null ptr. 1201 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) { 1202 if (F->getName() == kAsanModuleCtorName) continue; 1203 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0)); 1204 // Don't instrument CTORs that will run before asan.module_ctor. 1205 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue; 1206 poisonOneInitializer(*F, ModuleName); 1207 } 1208 } 1209 } 1210 1211 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) { 1212 Type *Ty = G->getValueType(); 1213 DEBUG(dbgs() << "GLOBAL: " << *G << "\n"); 1214 1215 if (GlobalsMD.get(G).IsBlacklisted) return false; 1216 if (!Ty->isSized()) return false; 1217 if (!G->hasInitializer()) return false; 1218 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global. 1219 // Touch only those globals that will not be defined in other modules. 1220 // Don't handle ODR linkage types and COMDATs since other modules may be built 1221 // without ASan. 1222 if (G->getLinkage() != GlobalVariable::ExternalLinkage && 1223 G->getLinkage() != GlobalVariable::PrivateLinkage && 1224 G->getLinkage() != GlobalVariable::InternalLinkage) 1225 return false; 1226 if (G->hasComdat()) return false; 1227 // Two problems with thread-locals: 1228 // - The address of the main thread's copy can't be computed at link-time. 1229 // - Need to poison all copies, not just the main thread's one. 1230 if (G->isThreadLocal()) return false; 1231 // For now, just ignore this Global if the alignment is large. 1232 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false; 1233 1234 if (G->hasSection()) { 1235 StringRef Section(G->getSection()); 1236 1237 // Globals from llvm.metadata aren't emitted, do not instrument them. 1238 if (Section == "llvm.metadata") return false; 1239 // Do not instrument globals from special LLVM sections. 1240 if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false; 1241 1242 // Do not instrument function pointers to initialization and termination 1243 // routines: dynamic linker will not properly handle redzones. 1244 if (Section.startswith(".preinit_array") || 1245 Section.startswith(".init_array") || 1246 Section.startswith(".fini_array")) { 1247 return false; 1248 } 1249 1250 // Callbacks put into the CRT initializer/terminator sections 1251 // should not be instrumented. 1252 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305 1253 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx 1254 if (Section.startswith(".CRT")) { 1255 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n"); 1256 return false; 1257 } 1258 1259 if (TargetTriple.isOSBinFormatMachO()) { 1260 StringRef ParsedSegment, ParsedSection; 1261 unsigned TAA = 0, StubSize = 0; 1262 bool TAAParsed; 1263 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier( 1264 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize); 1265 assert(ErrorCode.empty() && "Invalid section specifier."); 1266 1267 // Ignore the globals from the __OBJC section. The ObjC runtime assumes 1268 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to 1269 // them. 1270 if (ParsedSegment == "__OBJC" || 1271 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) { 1272 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n"); 1273 return false; 1274 } 1275 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32 1276 // Constant CFString instances are compiled in the following way: 1277 // -- the string buffer is emitted into 1278 // __TEXT,__cstring,cstring_literals 1279 // -- the constant NSConstantString structure referencing that buffer 1280 // is placed into __DATA,__cfstring 1281 // Therefore there's no point in placing redzones into __DATA,__cfstring. 1282 // Moreover, it causes the linker to crash on OS X 10.7 1283 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") { 1284 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n"); 1285 return false; 1286 } 1287 // The linker merges the contents of cstring_literals and removes the 1288 // trailing zeroes. 1289 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) { 1290 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n"); 1291 return false; 1292 } 1293 } 1294 } 1295 1296 return true; 1297 } 1298 1299 // On Mach-O platforms, we emit global metadata in a separate section of the 1300 // binary in order to allow the linker to properly dead strip. This is only 1301 // supported on recent versions of ld64. 1302 bool AddressSanitizerModule::ShouldUseMachOGlobalsSection() const { 1303 if (!TargetTriple.isOSBinFormatMachO()) 1304 return false; 1305 1306 if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11)) 1307 return true; 1308 if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9)) 1309 return true; 1310 if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2)) 1311 return true; 1312 1313 return false; 1314 } 1315 1316 void AddressSanitizerModule::initializeCallbacks(Module &M) { 1317 IRBuilder<> IRB(*C); 1318 1319 // Declare our poisoning and unpoisoning functions. 1320 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1321 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr)); 1322 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage); 1323 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1324 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr)); 1325 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage); 1326 1327 // Declare functions that register/unregister globals. 1328 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1329 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); 1330 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage); 1331 AsanUnregisterGlobals = checkSanitizerInterfaceFunction( 1332 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(), 1333 IntptrTy, IntptrTy, nullptr)); 1334 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage); 1335 1336 // Declare the functions that find globals in a shared object and then invoke 1337 // the (un)register function on them. 1338 AsanRegisterImageGlobals = checkSanitizerInterfaceFunction( 1339 M.getOrInsertFunction(kAsanRegisterImageGlobalsName, 1340 IRB.getVoidTy(), IntptrTy, nullptr)); 1341 AsanRegisterImageGlobals->setLinkage(Function::ExternalLinkage); 1342 1343 AsanUnregisterImageGlobals = checkSanitizerInterfaceFunction( 1344 M.getOrInsertFunction(kAsanUnregisterImageGlobalsName, 1345 IRB.getVoidTy(), IntptrTy, nullptr)); 1346 AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage); 1347 } 1348 1349 // This function replaces all global variables with new variables that have 1350 // trailing redzones. It also creates a function that poisons 1351 // redzones and inserts this function into llvm.global_ctors. 1352 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) { 1353 GlobalsMD.init(M); 1354 1355 SmallVector<GlobalVariable *, 16> GlobalsToChange; 1356 1357 for (auto &G : M.globals()) { 1358 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G); 1359 } 1360 1361 size_t n = GlobalsToChange.size(); 1362 if (n == 0) return false; 1363 1364 // A global is described by a structure 1365 // size_t beg; 1366 // size_t size; 1367 // size_t size_with_redzone; 1368 // const char *name; 1369 // const char *module_name; 1370 // size_t has_dynamic_init; 1371 // void *source_location; 1372 // size_t odr_indicator; 1373 // We initialize an array of such structures and pass it to a run-time call. 1374 StructType *GlobalStructTy = 1375 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy, 1376 IntptrTy, IntptrTy, IntptrTy, nullptr); 1377 SmallVector<Constant *, 16> Initializers(n); 1378 1379 bool HasDynamicallyInitializedGlobals = false; 1380 1381 // We shouldn't merge same module names, as this string serves as unique 1382 // module ID in runtime. 1383 GlobalVariable *ModuleName = createPrivateGlobalForString( 1384 M, M.getModuleIdentifier(), /*AllowMerging*/ false); 1385 1386 auto &DL = M.getDataLayout(); 1387 for (size_t i = 0; i < n; i++) { 1388 static const uint64_t kMaxGlobalRedzone = 1 << 18; 1389 GlobalVariable *G = GlobalsToChange[i]; 1390 1391 auto MD = GlobalsMD.get(G); 1392 StringRef NameForGlobal = G->getName(); 1393 // Create string holding the global name (use global name from metadata 1394 // if it's available, otherwise just write the name of global variable). 1395 GlobalVariable *Name = createPrivateGlobalForString( 1396 M, MD.Name.empty() ? NameForGlobal : MD.Name, 1397 /*AllowMerging*/ true); 1398 1399 Type *Ty = G->getValueType(); 1400 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty); 1401 uint64_t MinRZ = MinRedzoneSizeForGlobal(); 1402 // MinRZ <= RZ <= kMaxGlobalRedzone 1403 // and trying to make RZ to be ~ 1/4 of SizeInBytes. 1404 uint64_t RZ = std::max( 1405 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ)); 1406 uint64_t RightRedzoneSize = RZ; 1407 // Round up to MinRZ 1408 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ); 1409 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0); 1410 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize); 1411 1412 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr); 1413 Constant *NewInitializer = 1414 ConstantStruct::get(NewTy, G->getInitializer(), 1415 Constant::getNullValue(RightRedZoneTy), nullptr); 1416 1417 // Create a new global variable with enough space for a redzone. 1418 GlobalValue::LinkageTypes Linkage = G->getLinkage(); 1419 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage) 1420 Linkage = GlobalValue::InternalLinkage; 1421 GlobalVariable *NewGlobal = 1422 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer, 1423 "", G, G->getThreadLocalMode()); 1424 NewGlobal->copyAttributesFrom(G); 1425 NewGlobal->setAlignment(MinRZ); 1426 1427 Value *Indices2[2]; 1428 Indices2[0] = IRB.getInt32(0); 1429 Indices2[1] = IRB.getInt32(0); 1430 1431 G->replaceAllUsesWith( 1432 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true)); 1433 NewGlobal->takeName(G); 1434 G->eraseFromParent(); 1435 1436 Constant *SourceLoc; 1437 if (!MD.SourceLoc.empty()) { 1438 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc); 1439 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy); 1440 } else { 1441 SourceLoc = ConstantInt::get(IntptrTy, 0); 1442 } 1443 1444 Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy()); 1445 GlobalValue *InstrumentedGlobal = NewGlobal; 1446 1447 bool CanUsePrivateAliases = TargetTriple.isOSBinFormatELF(); 1448 if (CanUsePrivateAliases && ClUsePrivateAliasForGlobals) { 1449 // Create local alias for NewGlobal to avoid crash on ODR between 1450 // instrumented and non-instrumented libraries. 1451 auto *GA = GlobalAlias::create(GlobalValue::InternalLinkage, 1452 NameForGlobal + M.getName(), NewGlobal); 1453 1454 // With local aliases, we need to provide another externally visible 1455 // symbol __odr_asan_XXX to detect ODR violation. 1456 auto *ODRIndicatorSym = 1457 new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage, 1458 Constant::getNullValue(IRB.getInt8Ty()), 1459 kODRGenPrefix + NameForGlobal, nullptr, 1460 NewGlobal->getThreadLocalMode()); 1461 1462 // Set meaningful attributes for indicator symbol. 1463 ODRIndicatorSym->setVisibility(NewGlobal->getVisibility()); 1464 ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass()); 1465 ODRIndicatorSym->setAlignment(1); 1466 ODRIndicator = ODRIndicatorSym; 1467 InstrumentedGlobal = GA; 1468 } 1469 1470 Initializers[i] = ConstantStruct::get( 1471 GlobalStructTy, 1472 ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy), 1473 ConstantInt::get(IntptrTy, SizeInBytes), 1474 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize), 1475 ConstantExpr::getPointerCast(Name, IntptrTy), 1476 ConstantExpr::getPointerCast(ModuleName, IntptrTy), 1477 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, 1478 ConstantExpr::getPointerCast(ODRIndicator, IntptrTy), nullptr); 1479 1480 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true; 1481 1482 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n"); 1483 } 1484 1485 1486 GlobalVariable *AllGlobals = nullptr; 1487 GlobalVariable *RegisteredFlag = nullptr; 1488 1489 // On recent Mach-O platforms, we emit the global metadata in a way that 1490 // allows the linker to properly strip dead globals. 1491 if (ShouldUseMachOGlobalsSection()) { 1492 // RegisteredFlag serves two purposes. First, we can pass it to dladdr() 1493 // to look up the loaded image that contains it. Second, we can store in it 1494 // whether registration has already occurred, to prevent duplicate 1495 // registration. 1496 // 1497 // Common linkage allows us to coalesce needles defined in each object 1498 // file so that there's only one per shared library. 1499 RegisteredFlag = new GlobalVariable( 1500 M, IntptrTy, false, GlobalVariable::CommonLinkage, 1501 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName); 1502 1503 // We also emit a structure which binds the liveness of the global 1504 // variable to the metadata struct. 1505 StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy, nullptr); 1506 1507 for (size_t i = 0; i < n; i++) { 1508 GlobalVariable *Metadata = new GlobalVariable( 1509 M, GlobalStructTy, false, GlobalVariable::InternalLinkage, 1510 Initializers[i], ""); 1511 Metadata->setSection("__DATA,__asan_globals,regular"); 1512 Metadata->setAlignment(1); // don't leave padding in between 1513 1514 auto LivenessBinder = ConstantStruct::get(LivenessTy, 1515 Initializers[i]->getAggregateElement(0u), 1516 ConstantExpr::getPointerCast(Metadata, IntptrTy), 1517 nullptr); 1518 GlobalVariable *Liveness = new GlobalVariable( 1519 M, LivenessTy, false, GlobalVariable::InternalLinkage, 1520 LivenessBinder, ""); 1521 Liveness->setSection("__DATA,__asan_liveness,regular,live_support"); 1522 } 1523 } else { 1524 // On all other platfoms, we just emit an array of global metadata 1525 // structures. 1526 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n); 1527 AllGlobals = new GlobalVariable( 1528 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage, 1529 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), ""); 1530 } 1531 1532 // Create calls for poisoning before initializers run and unpoisoning after. 1533 if (HasDynamicallyInitializedGlobals) 1534 createInitializerPoisonCalls(M, ModuleName); 1535 1536 // Create a call to register the globals with the runtime. 1537 if (ShouldUseMachOGlobalsSection()) { 1538 IRB.CreateCall(AsanRegisterImageGlobals, 1539 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)}); 1540 } else { 1541 IRB.CreateCall(AsanRegisterGlobals, 1542 {IRB.CreatePointerCast(AllGlobals, IntptrTy), 1543 ConstantInt::get(IntptrTy, n)}); 1544 } 1545 1546 // We also need to unregister globals at the end, e.g., when a shared library 1547 // gets closed. 1548 Function *AsanDtorFunction = 1549 Function::Create(FunctionType::get(Type::getVoidTy(*C), false), 1550 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M); 1551 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction); 1552 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB)); 1553 1554 if (ShouldUseMachOGlobalsSection()) { 1555 IRB_Dtor.CreateCall(AsanUnregisterImageGlobals, 1556 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)}); 1557 } else { 1558 IRB_Dtor.CreateCall(AsanUnregisterGlobals, 1559 {IRB.CreatePointerCast(AllGlobals, IntptrTy), 1560 ConstantInt::get(IntptrTy, n)}); 1561 } 1562 1563 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority); 1564 1565 DEBUG(dbgs() << M); 1566 return true; 1567 } 1568 1569 bool AddressSanitizerModule::runOnModule(Module &M) { 1570 C = &(M.getContext()); 1571 int LongSize = M.getDataLayout().getPointerSizeInBits(); 1572 IntptrTy = Type::getIntNTy(*C, LongSize); 1573 TargetTriple = Triple(M.getTargetTriple()); 1574 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel); 1575 initializeCallbacks(M); 1576 1577 bool Changed = false; 1578 1579 // TODO(glider): temporarily disabled globals instrumentation for KASan. 1580 if (ClGlobals && !CompileKernel) { 1581 Function *CtorFunc = M.getFunction(kAsanModuleCtorName); 1582 assert(CtorFunc); 1583 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator()); 1584 Changed |= InstrumentGlobals(IRB, M); 1585 } 1586 1587 return Changed; 1588 } 1589 1590 void AddressSanitizer::initializeCallbacks(Module &M) { 1591 IRBuilder<> IRB(*C); 1592 // Create __asan_report* callbacks. 1593 // IsWrite, TypeSize and Exp are encoded in the function name. 1594 for (int Exp = 0; Exp < 2; Exp++) { 1595 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) { 1596 const std::string TypeStr = AccessIsWrite ? "store" : "load"; 1597 const std::string ExpStr = Exp ? "exp_" : ""; 1598 const std::string SuffixStr = CompileKernel ? "N" : "_n"; 1599 const std::string EndingStr = Recover ? "_noabort" : ""; 1600 Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr; 1601 AsanErrorCallbackSized[AccessIsWrite][Exp] = 1602 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1603 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr + EndingStr, 1604 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr)); 1605 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] = 1606 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1607 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr, 1608 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr)); 1609 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes; 1610 AccessSizeIndex++) { 1611 const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex); 1612 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] = 1613 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1614 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr, 1615 IRB.getVoidTy(), IntptrTy, ExpType, nullptr)); 1616 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] = 1617 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1618 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr, 1619 IRB.getVoidTy(), IntptrTy, ExpType, nullptr)); 1620 } 1621 } 1622 } 1623 1624 const std::string MemIntrinCallbackPrefix = 1625 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix; 1626 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1627 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(), 1628 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr)); 1629 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1630 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(), 1631 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr)); 1632 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1633 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(), 1634 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr)); 1635 1636 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction( 1637 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr)); 1638 1639 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1640 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); 1641 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1642 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); 1643 // We insert an empty inline asm after __asan_report* to avoid callback merge. 1644 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), 1645 StringRef(""), StringRef(""), 1646 /*hasSideEffects=*/true); 1647 } 1648 1649 // virtual 1650 bool AddressSanitizer::doInitialization(Module &M) { 1651 // Initialize the private fields. No one has accessed them before. 1652 1653 GlobalsMD.init(M); 1654 1655 C = &(M.getContext()); 1656 LongSize = M.getDataLayout().getPointerSizeInBits(); 1657 IntptrTy = Type::getIntNTy(*C, LongSize); 1658 TargetTriple = Triple(M.getTargetTriple()); 1659 1660 if (!CompileKernel) { 1661 std::tie(AsanCtorFunction, AsanInitFunction) = 1662 createSanitizerCtorAndInitFunctions( 1663 M, kAsanModuleCtorName, kAsanInitName, 1664 /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName); 1665 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority); 1666 } 1667 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel); 1668 return true; 1669 } 1670 1671 bool AddressSanitizer::doFinalization(Module &M) { 1672 GlobalsMD.reset(); 1673 return false; 1674 } 1675 1676 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) { 1677 // For each NSObject descendant having a +load method, this method is invoked 1678 // by the ObjC runtime before any of the static constructors is called. 1679 // Therefore we need to instrument such methods with a call to __asan_init 1680 // at the beginning in order to initialize our runtime before any access to 1681 // the shadow memory. 1682 // We cannot just ignore these methods, because they may call other 1683 // instrumented functions. 1684 if (F.getName().find(" load]") != std::string::npos) { 1685 IRBuilder<> IRB(&F.front(), F.front().begin()); 1686 IRB.CreateCall(AsanInitFunction, {}); 1687 return true; 1688 } 1689 return false; 1690 } 1691 1692 void AddressSanitizer::markEscapedLocalAllocas(Function &F) { 1693 // Find the one possible call to llvm.localescape and pre-mark allocas passed 1694 // to it as uninteresting. This assumes we haven't started processing allocas 1695 // yet. This check is done up front because iterating the use list in 1696 // isInterestingAlloca would be algorithmically slower. 1697 assert(ProcessedAllocas.empty() && "must process localescape before allocas"); 1698 1699 // Try to get the declaration of llvm.localescape. If it's not in the module, 1700 // we can exit early. 1701 if (!F.getParent()->getFunction("llvm.localescape")) return; 1702 1703 // Look for a call to llvm.localescape call in the entry block. It can't be in 1704 // any other block. 1705 for (Instruction &I : F.getEntryBlock()) { 1706 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I); 1707 if (II && II->getIntrinsicID() == Intrinsic::localescape) { 1708 // We found a call. Mark all the allocas passed in as uninteresting. 1709 for (Value *Arg : II->arg_operands()) { 1710 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts()); 1711 assert(AI && AI->isStaticAlloca() && 1712 "non-static alloca arg to localescape"); 1713 ProcessedAllocas[AI] = false; 1714 } 1715 break; 1716 } 1717 } 1718 } 1719 1720 bool AddressSanitizer::runOnFunction(Function &F) { 1721 if (&F == AsanCtorFunction) return false; 1722 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false; 1723 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n"); 1724 initializeCallbacks(*F.getParent()); 1725 1726 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); 1727 1728 // If needed, insert __asan_init before checking for SanitizeAddress attr. 1729 maybeInsertAsanInitAtFunctionEntry(F); 1730 1731 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false; 1732 1733 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false; 1734 1735 FunctionStateRAII CleanupObj(this); 1736 1737 // We can't instrument allocas used with llvm.localescape. Only static allocas 1738 // can be passed to that intrinsic. 1739 markEscapedLocalAllocas(F); 1740 1741 // We want to instrument every address only once per basic block (unless there 1742 // are calls between uses). 1743 SmallSet<Value *, 16> TempsToInstrument; 1744 SmallVector<Instruction *, 16> ToInstrument; 1745 SmallVector<Instruction *, 8> NoReturnCalls; 1746 SmallVector<BasicBlock *, 16> AllBlocks; 1747 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts; 1748 int NumAllocas = 0; 1749 bool IsWrite; 1750 unsigned Alignment; 1751 uint64_t TypeSize; 1752 1753 // Fill the set of memory operations to instrument. 1754 for (auto &BB : F) { 1755 AllBlocks.push_back(&BB); 1756 TempsToInstrument.clear(); 1757 int NumInsnsPerBB = 0; 1758 for (auto &Inst : BB) { 1759 if (LooksLikeCodeInBug11395(&Inst)) return false; 1760 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize, 1761 &Alignment)) { 1762 if (ClOpt && ClOptSameTemp) { 1763 if (!TempsToInstrument.insert(Addr).second) 1764 continue; // We've seen this temp in the current BB. 1765 } 1766 } else if (ClInvalidPointerPairs && 1767 isInterestingPointerComparisonOrSubtraction(&Inst)) { 1768 PointerComparisonsOrSubtracts.push_back(&Inst); 1769 continue; 1770 } else if (isa<MemIntrinsic>(Inst)) { 1771 // ok, take it. 1772 } else { 1773 if (isa<AllocaInst>(Inst)) NumAllocas++; 1774 CallSite CS(&Inst); 1775 if (CS) { 1776 // A call inside BB. 1777 TempsToInstrument.clear(); 1778 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction()); 1779 } 1780 continue; 1781 } 1782 ToInstrument.push_back(&Inst); 1783 NumInsnsPerBB++; 1784 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break; 1785 } 1786 } 1787 1788 bool UseCalls = 1789 CompileKernel || 1790 (ClInstrumentationWithCallsThreshold >= 0 && 1791 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold); 1792 const TargetLibraryInfo *TLI = 1793 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(); 1794 const DataLayout &DL = F.getParent()->getDataLayout(); 1795 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(), 1796 /*RoundToAlign=*/true); 1797 1798 // Instrument. 1799 int NumInstrumented = 0; 1800 for (auto Inst : ToInstrument) { 1801 if (ClDebugMin < 0 || ClDebugMax < 0 || 1802 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) { 1803 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment)) 1804 instrumentMop(ObjSizeVis, Inst, UseCalls, 1805 F.getParent()->getDataLayout()); 1806 else 1807 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst)); 1808 } 1809 NumInstrumented++; 1810 } 1811 1812 FunctionStackPoisoner FSP(F, *this); 1813 bool ChangedStack = FSP.runOnFunction(); 1814 1815 // We must unpoison the stack before every NoReturn call (throw, _exit, etc). 1816 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37 1817 for (auto CI : NoReturnCalls) { 1818 IRBuilder<> IRB(CI); 1819 IRB.CreateCall(AsanHandleNoReturnFunc, {}); 1820 } 1821 1822 for (auto Inst : PointerComparisonsOrSubtracts) { 1823 instrumentPointerComparisonOrSubtraction(Inst); 1824 NumInstrumented++; 1825 } 1826 1827 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty(); 1828 1829 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n"); 1830 1831 return res; 1832 } 1833 1834 // Workaround for bug 11395: we don't want to instrument stack in functions 1835 // with large assembly blobs (32-bit only), otherwise reg alloc may crash. 1836 // FIXME: remove once the bug 11395 is fixed. 1837 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) { 1838 if (LongSize != 32) return false; 1839 CallInst *CI = dyn_cast<CallInst>(I); 1840 if (!CI || !CI->isInlineAsm()) return false; 1841 if (CI->getNumArgOperands() <= 5) return false; 1842 // We have inline assembly with quite a few arguments. 1843 return true; 1844 } 1845 1846 void FunctionStackPoisoner::initializeCallbacks(Module &M) { 1847 IRBuilder<> IRB(*C); 1848 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) { 1849 std::string Suffix = itostr(i); 1850 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction( 1851 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy, 1852 IntptrTy, nullptr)); 1853 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction( 1854 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix, 1855 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); 1856 } 1857 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction( 1858 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(), 1859 IntptrTy, IntptrTy, nullptr)); 1860 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction( 1861 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), 1862 IntptrTy, IntptrTy, nullptr)); 1863 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1864 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); 1865 AsanAllocasUnpoisonFunc = 1866 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 1867 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); 1868 } 1869 1870 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes, 1871 IRBuilder<> &IRB, Value *ShadowBase, 1872 bool DoPoison) { 1873 size_t n = ShadowBytes.size(); 1874 size_t i = 0; 1875 // We need to (un)poison n bytes of stack shadow. Poison as many as we can 1876 // using 64-bit stores (if we are on 64-bit arch), then poison the rest 1877 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores. 1878 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8; 1879 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) { 1880 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) { 1881 uint64_t Val = 0; 1882 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) { 1883 if (F.getParent()->getDataLayout().isLittleEndian()) 1884 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j); 1885 else 1886 Val = (Val << 8) | ShadowBytes[i + j]; 1887 } 1888 if (!Val) continue; 1889 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)); 1890 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8); 1891 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0); 1892 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo())); 1893 } 1894 } 1895 } 1896 1897 // Fake stack allocator (asan_fake_stack.h) has 11 size classes 1898 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass 1899 static int StackMallocSizeClass(uint64_t LocalStackSize) { 1900 assert(LocalStackSize <= kMaxStackMallocSize); 1901 uint64_t MaxSize = kMinStackMallocSize; 1902 for (int i = 0;; i++, MaxSize *= 2) 1903 if (LocalStackSize <= MaxSize) return i; 1904 llvm_unreachable("impossible LocalStackSize"); 1905 } 1906 1907 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic. 1908 // We can not use MemSet intrinsic because it may end up calling the actual 1909 // memset. Size is a multiple of 8. 1910 // Currently this generates 8-byte stores on x86_64; it may be better to 1911 // generate wider stores. 1912 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined( 1913 IRBuilder<> &IRB, Value *ShadowBase, int Size) { 1914 assert(!(Size % 8)); 1915 1916 // kAsanStackAfterReturnMagic is 0xf5. 1917 const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL; 1918 1919 for (int i = 0; i < Size; i += 8) { 1920 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)); 1921 IRB.CreateStore( 1922 ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64), 1923 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo())); 1924 } 1925 } 1926 1927 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond, 1928 Value *ValueIfTrue, 1929 Instruction *ThenTerm, 1930 Value *ValueIfFalse) { 1931 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2); 1932 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent(); 1933 PHI->addIncoming(ValueIfFalse, CondBlock); 1934 BasicBlock *ThenBlock = ThenTerm->getParent(); 1935 PHI->addIncoming(ValueIfTrue, ThenBlock); 1936 return PHI; 1937 } 1938 1939 Value *FunctionStackPoisoner::createAllocaForLayout( 1940 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) { 1941 AllocaInst *Alloca; 1942 if (Dynamic) { 1943 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(), 1944 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize), 1945 "MyAlloca"); 1946 } else { 1947 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize), 1948 nullptr, "MyAlloca"); 1949 assert(Alloca->isStaticAlloca()); 1950 } 1951 assert((ClRealignStack & (ClRealignStack - 1)) == 0); 1952 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack); 1953 Alloca->setAlignment(FrameAlignment); 1954 return IRB.CreatePointerCast(Alloca, IntptrTy); 1955 } 1956 1957 void FunctionStackPoisoner::createDynamicAllocasInitStorage() { 1958 BasicBlock &FirstBB = *F.begin(); 1959 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin())); 1960 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr); 1961 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout); 1962 DynamicAllocaLayout->setAlignment(32); 1963 } 1964 1965 void FunctionStackPoisoner::poisonStack() { 1966 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0); 1967 1968 // Insert poison calls for lifetime intrinsics for alloca. 1969 bool HavePoisonedAllocas = false; 1970 for (const auto &APC : AllocaPoisonCallVec) { 1971 assert(APC.InsBefore); 1972 assert(APC.AI); 1973 IRBuilder<> IRB(APC.InsBefore); 1974 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison); 1975 HavePoisonedAllocas |= APC.DoPoison; 1976 } 1977 1978 if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) { 1979 // Handle dynamic allocas. 1980 createDynamicAllocasInitStorage(); 1981 for (auto &AI : DynamicAllocaVec) handleDynamicAllocaCall(AI); 1982 1983 unpoisonDynamicAllocas(); 1984 } 1985 1986 if (AllocaVec.empty()) return; 1987 1988 int StackMallocIdx = -1; 1989 DebugLoc EntryDebugLocation; 1990 if (auto SP = F.getSubprogram()) 1991 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP); 1992 1993 Instruction *InsBefore = AllocaVec[0]; 1994 IRBuilder<> IRB(InsBefore); 1995 IRB.SetCurrentDebugLocation(EntryDebugLocation); 1996 1997 // Make sure non-instrumented allocas stay in the entry block. Otherwise, 1998 // debug info is broken, because only entry-block allocas are treated as 1999 // regular stack slots. 2000 auto InsBeforeB = InsBefore->getParent(); 2001 assert(InsBeforeB == &F.getEntryBlock()); 2002 for (BasicBlock::iterator I(InsBefore); I != InsBeforeB->end(); ++I) 2003 if (auto *AI = dyn_cast<AllocaInst>(I)) 2004 if (NonInstrumentedStaticAllocaVec.count(AI) > 0) 2005 AI->moveBefore(InsBefore); 2006 2007 // If we have a call to llvm.localescape, keep it in the entry block. 2008 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore); 2009 2010 SmallVector<ASanStackVariableDescription, 16> SVD; 2011 SVD.reserve(AllocaVec.size()); 2012 for (AllocaInst *AI : AllocaVec) { 2013 ASanStackVariableDescription D = {AI->getName().data(), 2014 ASan.getAllocaSizeInBytes(AI), 2015 AI->getAlignment(), AI, 0}; 2016 SVD.push_back(D); 2017 } 2018 // Minimal header size (left redzone) is 4 pointers, 2019 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms. 2020 size_t MinHeaderSize = ASan.LongSize / 2; 2021 ASanStackFrameLayout L; 2022 ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize, &L); 2023 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n"); 2024 uint64_t LocalStackSize = L.FrameSize; 2025 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel && 2026 LocalStackSize <= kMaxStackMallocSize; 2027 bool DoDynamicAlloca = ClDynamicAllocaStack; 2028 // Don't do dynamic alloca or stack malloc if: 2029 // 1) There is inline asm: too often it makes assumptions on which registers 2030 // are available. 2031 // 2) There is a returns_twice call (typically setjmp), which is 2032 // optimization-hostile, and doesn't play well with introduced indirect 2033 // register-relative calculation of local variable addresses. 2034 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall; 2035 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall; 2036 2037 Value *StaticAlloca = 2038 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false); 2039 2040 Value *FakeStack; 2041 Value *LocalStackBase; 2042 2043 if (DoStackMalloc) { 2044 // void *FakeStack = __asan_option_detect_stack_use_after_return 2045 // ? __asan_stack_malloc_N(LocalStackSize) 2046 // : nullptr; 2047 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize); 2048 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal( 2049 kAsanOptionDetectUAR, IRB.getInt32Ty()); 2050 Value *UARIsEnabled = 2051 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR), 2052 Constant::getNullValue(IRB.getInt32Ty())); 2053 Instruction *Term = 2054 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false); 2055 IRBuilder<> IRBIf(Term); 2056 IRBIf.SetCurrentDebugLocation(EntryDebugLocation); 2057 StackMallocIdx = StackMallocSizeClass(LocalStackSize); 2058 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass); 2059 Value *FakeStackValue = 2060 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx], 2061 ConstantInt::get(IntptrTy, LocalStackSize)); 2062 IRB.SetInsertPoint(InsBefore); 2063 IRB.SetCurrentDebugLocation(EntryDebugLocation); 2064 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term, 2065 ConstantInt::get(IntptrTy, 0)); 2066 2067 Value *NoFakeStack = 2068 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy)); 2069 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false); 2070 IRBIf.SetInsertPoint(Term); 2071 IRBIf.SetCurrentDebugLocation(EntryDebugLocation); 2072 Value *AllocaValue = 2073 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca; 2074 IRB.SetInsertPoint(InsBefore); 2075 IRB.SetCurrentDebugLocation(EntryDebugLocation); 2076 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack); 2077 } else { 2078 // void *FakeStack = nullptr; 2079 // void *LocalStackBase = alloca(LocalStackSize); 2080 FakeStack = ConstantInt::get(IntptrTy, 0); 2081 LocalStackBase = 2082 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca; 2083 } 2084 2085 // Replace Alloca instructions with base+offset. 2086 for (const auto &Desc : SVD) { 2087 AllocaInst *AI = Desc.AI; 2088 Value *NewAllocaPtr = IRB.CreateIntToPtr( 2089 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)), 2090 AI->getType()); 2091 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true); 2092 AI->replaceAllUsesWith(NewAllocaPtr); 2093 } 2094 2095 // The left-most redzone has enough space for at least 4 pointers. 2096 // Write the Magic value to redzone[0]. 2097 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy); 2098 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic), 2099 BasePlus0); 2100 // Write the frame description constant to redzone[1]. 2101 Value *BasePlus1 = IRB.CreateIntToPtr( 2102 IRB.CreateAdd(LocalStackBase, 2103 ConstantInt::get(IntptrTy, ASan.LongSize / 8)), 2104 IntptrPtrTy); 2105 GlobalVariable *StackDescriptionGlobal = 2106 createPrivateGlobalForString(*F.getParent(), L.DescriptionString, 2107 /*AllowMerging*/ true); 2108 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy); 2109 IRB.CreateStore(Description, BasePlus1); 2110 // Write the PC to redzone[2]. 2111 Value *BasePlus2 = IRB.CreateIntToPtr( 2112 IRB.CreateAdd(LocalStackBase, 2113 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)), 2114 IntptrPtrTy); 2115 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2); 2116 2117 // Poison the stack redzones at the entry. 2118 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB); 2119 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true); 2120 2121 // (Un)poison the stack before all ret instructions. 2122 for (auto Ret : RetVec) { 2123 IRBuilder<> IRBRet(Ret); 2124 // Mark the current frame as retired. 2125 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic), 2126 BasePlus0); 2127 if (DoStackMalloc) { 2128 assert(StackMallocIdx >= 0); 2129 // if FakeStack != 0 // LocalStackBase == FakeStack 2130 // // In use-after-return mode, poison the whole stack frame. 2131 // if StackMallocIdx <= 4 2132 // // For small sizes inline the whole thing: 2133 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize); 2134 // **SavedFlagPtr(FakeStack) = 0 2135 // else 2136 // __asan_stack_free_N(FakeStack, LocalStackSize) 2137 // else 2138 // <This is not a fake stack; unpoison the redzones> 2139 Value *Cmp = 2140 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy)); 2141 TerminatorInst *ThenTerm, *ElseTerm; 2142 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm); 2143 2144 IRBuilder<> IRBPoison(ThenTerm); 2145 if (StackMallocIdx <= 4) { 2146 int ClassSize = kMinStackMallocSize << StackMallocIdx; 2147 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase, 2148 ClassSize >> Mapping.Scale); 2149 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd( 2150 FakeStack, 2151 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8)); 2152 Value *SavedFlagPtr = IRBPoison.CreateLoad( 2153 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy)); 2154 IRBPoison.CreateStore( 2155 Constant::getNullValue(IRBPoison.getInt8Ty()), 2156 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy())); 2157 } else { 2158 // For larger frames call __asan_stack_free_*. 2159 IRBPoison.CreateCall( 2160 AsanStackFreeFunc[StackMallocIdx], 2161 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)}); 2162 } 2163 2164 IRBuilder<> IRBElse(ElseTerm); 2165 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false); 2166 } else if (HavePoisonedAllocas) { 2167 // If we poisoned some allocas in llvm.lifetime analysis, 2168 // unpoison whole stack frame now. 2169 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false); 2170 } else { 2171 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false); 2172 } 2173 } 2174 2175 // We are done. Remove the old unused alloca instructions. 2176 for (auto AI : AllocaVec) AI->eraseFromParent(); 2177 } 2178 2179 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size, 2180 IRBuilder<> &IRB, bool DoPoison) { 2181 // For now just insert the call to ASan runtime. 2182 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy); 2183 Value *SizeArg = ConstantInt::get(IntptrTy, Size); 2184 IRB.CreateCall( 2185 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc, 2186 {AddrArg, SizeArg}); 2187 } 2188 2189 // Handling llvm.lifetime intrinsics for a given %alloca: 2190 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca. 2191 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect 2192 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory 2193 // could be poisoned by previous llvm.lifetime.end instruction, as the 2194 // variable may go in and out of scope several times, e.g. in loops). 2195 // (3) if we poisoned at least one %alloca in a function, 2196 // unpoison the whole stack frame at function exit. 2197 2198 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) { 2199 if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) 2200 // We're intested only in allocas we can handle. 2201 return ASan.isInterestingAlloca(*AI) ? AI : nullptr; 2202 // See if we've already calculated (or started to calculate) alloca for a 2203 // given value. 2204 AllocaForValueMapTy::iterator I = AllocaForValue.find(V); 2205 if (I != AllocaForValue.end()) return I->second; 2206 // Store 0 while we're calculating alloca for value V to avoid 2207 // infinite recursion if the value references itself. 2208 AllocaForValue[V] = nullptr; 2209 AllocaInst *Res = nullptr; 2210 if (CastInst *CI = dyn_cast<CastInst>(V)) 2211 Res = findAllocaForValue(CI->getOperand(0)); 2212 else if (PHINode *PN = dyn_cast<PHINode>(V)) { 2213 for (Value *IncValue : PN->incoming_values()) { 2214 // Allow self-referencing phi-nodes. 2215 if (IncValue == PN) continue; 2216 AllocaInst *IncValueAI = findAllocaForValue(IncValue); 2217 // AI for incoming values should exist and should all be equal. 2218 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res)) 2219 return nullptr; 2220 Res = IncValueAI; 2221 } 2222 } 2223 if (Res) AllocaForValue[V] = Res; 2224 return Res; 2225 } 2226 2227 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) { 2228 IRBuilder<> IRB(AI); 2229 2230 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment()); 2231 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1; 2232 2233 Value *Zero = Constant::getNullValue(IntptrTy); 2234 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize); 2235 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask); 2236 2237 // Since we need to extend alloca with additional memory to locate 2238 // redzones, and OldSize is number of allocated blocks with 2239 // ElementSize size, get allocated memory size in bytes by 2240 // OldSize * ElementSize. 2241 const unsigned ElementSize = 2242 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType()); 2243 Value *OldSize = 2244 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false), 2245 ConstantInt::get(IntptrTy, ElementSize)); 2246 2247 // PartialSize = OldSize % 32 2248 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask); 2249 2250 // Misalign = kAllocaRzSize - PartialSize; 2251 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize); 2252 2253 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0; 2254 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize); 2255 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero); 2256 2257 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize 2258 // Align is added to locate left redzone, PartialPadding for possible 2259 // partial redzone and kAllocaRzSize for right redzone respectively. 2260 Value *AdditionalChunkSize = IRB.CreateAdd( 2261 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding); 2262 2263 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize); 2264 2265 // Insert new alloca with new NewSize and Align params. 2266 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize); 2267 NewAlloca->setAlignment(Align); 2268 2269 // NewAddress = Address + Align 2270 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy), 2271 ConstantInt::get(IntptrTy, Align)); 2272 2273 // Insert __asan_alloca_poison call for new created alloca. 2274 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize}); 2275 2276 // Store the last alloca's address to DynamicAllocaLayout. We'll need this 2277 // for unpoisoning stuff. 2278 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout); 2279 2280 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType()); 2281 2282 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr. 2283 AI->replaceAllUsesWith(NewAddressPtr); 2284 2285 // We are done. Erase old alloca from parent. 2286 AI->eraseFromParent(); 2287 } 2288 2289 // isSafeAccess returns true if Addr is always inbounds with respect to its 2290 // base object. For example, it is a field access or an array access with 2291 // constant inbounds index. 2292 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, 2293 Value *Addr, uint64_t TypeSize) const { 2294 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr); 2295 if (!ObjSizeVis.bothKnown(SizeOffset)) return false; 2296 uint64_t Size = SizeOffset.first.getZExtValue(); 2297 int64_t Offset = SizeOffset.second.getSExtValue(); 2298 // Three checks are required to ensure safety: 2299 // . Offset >= 0 (since the offset is given from the base ptr) 2300 // . Size >= Offset (unsigned) 2301 // . Size - Offset >= NeededSize (unsigned) 2302 return Offset >= 0 && Size >= uint64_t(Offset) && 2303 Size - uint64_t(Offset) >= TypeSize / 8; 2304 } 2305