1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * UBSAN error reporting functions 4 * 5 * Copyright (c) 2014 Samsung Electronics Co., Ltd. 6 * Author: Andrey Ryabinin <[email protected]> 7 */ 8 9 #include <linux/bitops.h> 10 #include <linux/bug.h> 11 #include <linux/ctype.h> 12 #include <linux/init.h> 13 #include <linux/kernel.h> 14 #include <linux/types.h> 15 #include <linux/sched.h> 16 #include <linux/uaccess.h> 17 18 #include "ubsan.h" 19 20 const char *type_check_kinds[] = { 21 "load of", 22 "store to", 23 "reference binding to", 24 "member access within", 25 "member call on", 26 "constructor call on", 27 "downcast of", 28 "downcast of" 29 }; 30 31 #define REPORTED_BIT 31 32 33 #if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN) 34 #define COLUMN_MASK (~(1U << REPORTED_BIT)) 35 #define LINE_MASK (~0U) 36 #else 37 #define COLUMN_MASK (~0U) 38 #define LINE_MASK (~(1U << REPORTED_BIT)) 39 #endif 40 41 #define VALUE_LENGTH 40 42 43 static bool was_reported(struct source_location *location) 44 { 45 return test_and_set_bit(REPORTED_BIT, &location->reported); 46 } 47 48 static void print_source_location(const char *prefix, 49 struct source_location *loc) 50 { 51 pr_err("%s %s:%d:%d\n", prefix, loc->file_name, 52 loc->line & LINE_MASK, loc->column & COLUMN_MASK); 53 } 54 55 static bool suppress_report(struct source_location *loc) 56 { 57 return current->in_ubsan || was_reported(loc); 58 } 59 60 static bool type_is_int(struct type_descriptor *type) 61 { 62 return type->type_kind == type_kind_int; 63 } 64 65 static bool type_is_signed(struct type_descriptor *type) 66 { 67 WARN_ON(!type_is_int(type)); 68 return type->type_info & 1; 69 } 70 71 static unsigned type_bit_width(struct type_descriptor *type) 72 { 73 return 1 << (type->type_info >> 1); 74 } 75 76 static bool is_inline_int(struct type_descriptor *type) 77 { 78 unsigned inline_bits = sizeof(unsigned long)*8; 79 unsigned bits = type_bit_width(type); 80 81 WARN_ON(!type_is_int(type)); 82 83 return bits <= inline_bits; 84 } 85 86 static s_max get_signed_val(struct type_descriptor *type, void *val) 87 { 88 if (is_inline_int(type)) { 89 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type); 90 unsigned long ulong_val = (unsigned long)val; 91 92 return ((s_max)ulong_val) << extra_bits >> extra_bits; 93 } 94 95 if (type_bit_width(type) == 64) 96 return *(s64 *)val; 97 98 return *(s_max *)val; 99 } 100 101 static bool val_is_negative(struct type_descriptor *type, void *val) 102 { 103 return type_is_signed(type) && get_signed_val(type, val) < 0; 104 } 105 106 static u_max get_unsigned_val(struct type_descriptor *type, void *val) 107 { 108 if (is_inline_int(type)) 109 return (unsigned long)val; 110 111 if (type_bit_width(type) == 64) 112 return *(u64 *)val; 113 114 return *(u_max *)val; 115 } 116 117 static void val_to_string(char *str, size_t size, struct type_descriptor *type, 118 void *value) 119 { 120 if (type_is_int(type)) { 121 if (type_bit_width(type) == 128) { 122 #if defined(CONFIG_ARCH_SUPPORTS_INT128) 123 u_max val = get_unsigned_val(type, value); 124 125 scnprintf(str, size, "0x%08x%08x%08x%08x", 126 (u32)(val >> 96), 127 (u32)(val >> 64), 128 (u32)(val >> 32), 129 (u32)(val)); 130 #else 131 WARN_ON(1); 132 #endif 133 } else if (type_is_signed(type)) { 134 scnprintf(str, size, "%lld", 135 (s64)get_signed_val(type, value)); 136 } else { 137 scnprintf(str, size, "%llu", 138 (u64)get_unsigned_val(type, value)); 139 } 140 } 141 } 142 143 static void ubsan_prologue(struct source_location *location) 144 { 145 current->in_ubsan++; 146 147 pr_err("========================================" 148 "========================================\n"); 149 print_source_location("UBSAN: Undefined behaviour in", location); 150 } 151 152 static void ubsan_epilogue(void) 153 { 154 dump_stack(); 155 pr_err("========================================" 156 "========================================\n"); 157 158 current->in_ubsan--; 159 160 if (panic_on_warn) { 161 /* 162 * This thread may hit another WARN() in the panic path. 163 * Resetting this prevents additional WARN() from panicking the 164 * system on this thread. Other threads are blocked by the 165 * panic_mutex in panic(). 166 */ 167 panic_on_warn = 0; 168 panic("panic_on_warn set ...\n"); 169 } 170 } 171 172 static void handle_overflow(struct overflow_data *data, void *lhs, 173 void *rhs, char op) 174 { 175 176 struct type_descriptor *type = data->type; 177 char lhs_val_str[VALUE_LENGTH]; 178 char rhs_val_str[VALUE_LENGTH]; 179 180 if (suppress_report(&data->location)) 181 return; 182 183 ubsan_prologue(&data->location); 184 185 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs); 186 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs); 187 pr_err("%s integer overflow:\n", 188 type_is_signed(type) ? "signed" : "unsigned"); 189 pr_err("%s %c %s cannot be represented in type %s\n", 190 lhs_val_str, 191 op, 192 rhs_val_str, 193 type->type_name); 194 195 ubsan_epilogue(); 196 } 197 198 void __ubsan_handle_add_overflow(struct overflow_data *data, 199 void *lhs, void *rhs) 200 { 201 202 handle_overflow(data, lhs, rhs, '+'); 203 } 204 EXPORT_SYMBOL(__ubsan_handle_add_overflow); 205 206 void __ubsan_handle_sub_overflow(struct overflow_data *data, 207 void *lhs, void *rhs) 208 { 209 handle_overflow(data, lhs, rhs, '-'); 210 } 211 EXPORT_SYMBOL(__ubsan_handle_sub_overflow); 212 213 void __ubsan_handle_mul_overflow(struct overflow_data *data, 214 void *lhs, void *rhs) 215 { 216 handle_overflow(data, lhs, rhs, '*'); 217 } 218 EXPORT_SYMBOL(__ubsan_handle_mul_overflow); 219 220 void __ubsan_handle_negate_overflow(struct overflow_data *data, 221 void *old_val) 222 { 223 char old_val_str[VALUE_LENGTH]; 224 225 if (suppress_report(&data->location)) 226 return; 227 228 ubsan_prologue(&data->location); 229 230 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); 231 232 pr_err("negation of %s cannot be represented in type %s:\n", 233 old_val_str, data->type->type_name); 234 235 ubsan_epilogue(); 236 } 237 EXPORT_SYMBOL(__ubsan_handle_negate_overflow); 238 239 240 void __ubsan_handle_divrem_overflow(struct overflow_data *data, 241 void *lhs, void *rhs) 242 { 243 char rhs_val_str[VALUE_LENGTH]; 244 245 if (suppress_report(&data->location)) 246 return; 247 248 ubsan_prologue(&data->location); 249 250 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 251 252 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 253 pr_err("division of %s by -1 cannot be represented in type %s\n", 254 rhs_val_str, data->type->type_name); 255 else 256 pr_err("division by zero\n"); 257 258 ubsan_epilogue(); 259 } 260 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 261 262 static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 263 { 264 if (suppress_report(data->location)) 265 return; 266 267 ubsan_prologue(data->location); 268 269 pr_err("%s null pointer of type %s\n", 270 type_check_kinds[data->type_check_kind], 271 data->type->type_name); 272 273 ubsan_epilogue(); 274 } 275 276 static void handle_misaligned_access(struct type_mismatch_data_common *data, 277 unsigned long ptr) 278 { 279 if (suppress_report(data->location)) 280 return; 281 282 ubsan_prologue(data->location); 283 284 pr_err("%s misaligned address %p for type %s\n", 285 type_check_kinds[data->type_check_kind], 286 (void *)ptr, data->type->type_name); 287 pr_err("which requires %ld byte alignment\n", data->alignment); 288 289 ubsan_epilogue(); 290 } 291 292 static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 293 unsigned long ptr) 294 { 295 if (suppress_report(data->location)) 296 return; 297 298 ubsan_prologue(data->location); 299 pr_err("%s address %p with insufficient space\n", 300 type_check_kinds[data->type_check_kind], 301 (void *) ptr); 302 pr_err("for an object of type %s\n", data->type->type_name); 303 ubsan_epilogue(); 304 } 305 306 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 307 unsigned long ptr) 308 { 309 unsigned long flags = user_access_save(); 310 311 if (!ptr) 312 handle_null_ptr_deref(data); 313 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 314 handle_misaligned_access(data, ptr); 315 else 316 handle_object_size_mismatch(data, ptr); 317 318 user_access_restore(flags); 319 } 320 321 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 322 void *ptr) 323 { 324 struct type_mismatch_data_common common_data = { 325 .location = &data->location, 326 .type = data->type, 327 .alignment = data->alignment, 328 .type_check_kind = data->type_check_kind 329 }; 330 331 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 332 } 333 EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 334 335 void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data, 336 void *ptr) 337 { 338 339 struct type_mismatch_data_common common_data = { 340 .location = &data->location, 341 .type = data->type, 342 .alignment = 1UL << data->log_alignment, 343 .type_check_kind = data->type_check_kind 344 }; 345 346 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 347 } 348 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 349 350 void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index) 351 { 352 char index_str[VALUE_LENGTH]; 353 354 if (suppress_report(&data->location)) 355 return; 356 357 ubsan_prologue(&data->location); 358 359 val_to_string(index_str, sizeof(index_str), data->index_type, index); 360 pr_err("index %s is out of range for type %s\n", index_str, 361 data->array_type->type_name); 362 ubsan_epilogue(); 363 } 364 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 365 366 void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data, 367 void *lhs, void *rhs) 368 { 369 struct type_descriptor *rhs_type = data->rhs_type; 370 struct type_descriptor *lhs_type = data->lhs_type; 371 char rhs_str[VALUE_LENGTH]; 372 char lhs_str[VALUE_LENGTH]; 373 unsigned long ua_flags = user_access_save(); 374 375 if (suppress_report(&data->location)) 376 goto out; 377 378 ubsan_prologue(&data->location); 379 380 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 381 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 382 383 if (val_is_negative(rhs_type, rhs)) 384 pr_err("shift exponent %s is negative\n", rhs_str); 385 386 else if (get_unsigned_val(rhs_type, rhs) >= 387 type_bit_width(lhs_type)) 388 pr_err("shift exponent %s is too large for %u-bit type %s\n", 389 rhs_str, 390 type_bit_width(lhs_type), 391 lhs_type->type_name); 392 else if (val_is_negative(lhs_type, lhs)) 393 pr_err("left shift of negative value %s\n", 394 lhs_str); 395 else 396 pr_err("left shift of %s by %s places cannot be" 397 " represented in type %s\n", 398 lhs_str, rhs_str, 399 lhs_type->type_name); 400 401 ubsan_epilogue(); 402 out: 403 user_access_restore(ua_flags); 404 } 405 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 406 407 408 void __ubsan_handle_builtin_unreachable(struct unreachable_data *data) 409 { 410 ubsan_prologue(&data->location); 411 pr_err("calling __builtin_unreachable()\n"); 412 ubsan_epilogue(); 413 panic("can't return from __builtin_unreachable()"); 414 } 415 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 416 417 void __ubsan_handle_load_invalid_value(struct invalid_value_data *data, 418 void *val) 419 { 420 char val_str[VALUE_LENGTH]; 421 422 if (suppress_report(&data->location)) 423 return; 424 425 ubsan_prologue(&data->location); 426 427 val_to_string(val_str, sizeof(val_str), data->type, val); 428 429 pr_err("load of value %s is not a valid value for type %s\n", 430 val_str, data->type->type_name); 431 432 ubsan_epilogue(); 433 } 434 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 435