1 /* 2 * UBSAN error reporting functions 3 * 4 * Copyright (c) 2014 Samsung Electronics Co., Ltd. 5 * Author: Andrey Ryabinin <[email protected]> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 */ 12 13 #include <linux/bitops.h> 14 #include <linux/bug.h> 15 #include <linux/ctype.h> 16 #include <linux/init.h> 17 #include <linux/kernel.h> 18 #include <linux/types.h> 19 #include <linux/sched.h> 20 21 #include "ubsan.h" 22 23 const char *type_check_kinds[] = { 24 "load of", 25 "store to", 26 "reference binding to", 27 "member access within", 28 "member call on", 29 "constructor call on", 30 "downcast of", 31 "downcast of" 32 }; 33 34 #define REPORTED_BIT 31 35 36 #if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN) 37 #define COLUMN_MASK (~(1U << REPORTED_BIT)) 38 #define LINE_MASK (~0U) 39 #else 40 #define COLUMN_MASK (~0U) 41 #define LINE_MASK (~(1U << REPORTED_BIT)) 42 #endif 43 44 #define VALUE_LENGTH 40 45 46 static bool was_reported(struct source_location *location) 47 { 48 return test_and_set_bit(REPORTED_BIT, &location->reported); 49 } 50 51 static void print_source_location(const char *prefix, 52 struct source_location *loc) 53 { 54 pr_err("%s %s:%d:%d\n", prefix, loc->file_name, 55 loc->line & LINE_MASK, loc->column & COLUMN_MASK); 56 } 57 58 static bool suppress_report(struct source_location *loc) 59 { 60 return current->in_ubsan || was_reported(loc); 61 } 62 63 static bool type_is_int(struct type_descriptor *type) 64 { 65 return type->type_kind == type_kind_int; 66 } 67 68 static bool type_is_signed(struct type_descriptor *type) 69 { 70 WARN_ON(!type_is_int(type)); 71 return type->type_info & 1; 72 } 73 74 static unsigned type_bit_width(struct type_descriptor *type) 75 { 76 return 1 << (type->type_info >> 1); 77 } 78 79 static bool is_inline_int(struct type_descriptor *type) 80 { 81 unsigned inline_bits = sizeof(unsigned long)*8; 82 unsigned bits = type_bit_width(type); 83 84 WARN_ON(!type_is_int(type)); 85 86 return bits <= inline_bits; 87 } 88 89 static s_max get_signed_val(struct type_descriptor *type, void *val) 90 { 91 if (is_inline_int(type)) { 92 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type); 93 unsigned long ulong_val = (unsigned long)val; 94 95 return ((s_max)ulong_val) << extra_bits >> extra_bits; 96 } 97 98 if (type_bit_width(type) == 64) 99 return *(s64 *)val; 100 101 return *(s_max *)val; 102 } 103 104 static bool val_is_negative(struct type_descriptor *type, void *val) 105 { 106 return type_is_signed(type) && get_signed_val(type, val) < 0; 107 } 108 109 static u_max get_unsigned_val(struct type_descriptor *type, void *val) 110 { 111 if (is_inline_int(type)) 112 return (unsigned long)val; 113 114 if (type_bit_width(type) == 64) 115 return *(u64 *)val; 116 117 return *(u_max *)val; 118 } 119 120 static void val_to_string(char *str, size_t size, struct type_descriptor *type, 121 void *value) 122 { 123 if (type_is_int(type)) { 124 if (type_bit_width(type) == 128) { 125 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__) 126 u_max val = get_unsigned_val(type, value); 127 128 scnprintf(str, size, "0x%08x%08x%08x%08x", 129 (u32)(val >> 96), 130 (u32)(val >> 64), 131 (u32)(val >> 32), 132 (u32)(val)); 133 #else 134 WARN_ON(1); 135 #endif 136 } else if (type_is_signed(type)) { 137 scnprintf(str, size, "%lld", 138 (s64)get_signed_val(type, value)); 139 } else { 140 scnprintf(str, size, "%llu", 141 (u64)get_unsigned_val(type, value)); 142 } 143 } 144 } 145 146 static DEFINE_SPINLOCK(report_lock); 147 148 static void ubsan_prologue(struct source_location *location, 149 unsigned long *flags) 150 { 151 current->in_ubsan++; 152 spin_lock_irqsave(&report_lock, *flags); 153 154 pr_err("========================================" 155 "========================================\n"); 156 print_source_location("UBSAN: Undefined behaviour in", location); 157 } 158 159 static void ubsan_epilogue(unsigned long *flags) 160 { 161 dump_stack(); 162 pr_err("========================================" 163 "========================================\n"); 164 spin_unlock_irqrestore(&report_lock, *flags); 165 current->in_ubsan--; 166 } 167 168 static void handle_overflow(struct overflow_data *data, void *lhs, 169 void *rhs, char op) 170 { 171 172 struct type_descriptor *type = data->type; 173 unsigned long flags; 174 char lhs_val_str[VALUE_LENGTH]; 175 char rhs_val_str[VALUE_LENGTH]; 176 177 if (suppress_report(&data->location)) 178 return; 179 180 ubsan_prologue(&data->location, &flags); 181 182 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs); 183 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs); 184 pr_err("%s integer overflow:\n", 185 type_is_signed(type) ? "signed" : "unsigned"); 186 pr_err("%s %c %s cannot be represented in type %s\n", 187 lhs_val_str, 188 op, 189 rhs_val_str, 190 type->type_name); 191 192 ubsan_epilogue(&flags); 193 } 194 195 void __ubsan_handle_add_overflow(struct overflow_data *data, 196 void *lhs, void *rhs) 197 { 198 199 handle_overflow(data, lhs, rhs, '+'); 200 } 201 EXPORT_SYMBOL(__ubsan_handle_add_overflow); 202 203 void __ubsan_handle_sub_overflow(struct overflow_data *data, 204 void *lhs, void *rhs) 205 { 206 handle_overflow(data, lhs, rhs, '-'); 207 } 208 EXPORT_SYMBOL(__ubsan_handle_sub_overflow); 209 210 void __ubsan_handle_mul_overflow(struct overflow_data *data, 211 void *lhs, void *rhs) 212 { 213 handle_overflow(data, lhs, rhs, '*'); 214 } 215 EXPORT_SYMBOL(__ubsan_handle_mul_overflow); 216 217 void __ubsan_handle_negate_overflow(struct overflow_data *data, 218 void *old_val) 219 { 220 unsigned long flags; 221 char old_val_str[VALUE_LENGTH]; 222 223 if (suppress_report(&data->location)) 224 return; 225 226 ubsan_prologue(&data->location, &flags); 227 228 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); 229 230 pr_err("negation of %s cannot be represented in type %s:\n", 231 old_val_str, data->type->type_name); 232 233 ubsan_epilogue(&flags); 234 } 235 EXPORT_SYMBOL(__ubsan_handle_negate_overflow); 236 237 238 void __ubsan_handle_divrem_overflow(struct overflow_data *data, 239 void *lhs, void *rhs) 240 { 241 unsigned long flags; 242 char rhs_val_str[VALUE_LENGTH]; 243 244 if (suppress_report(&data->location)) 245 return; 246 247 ubsan_prologue(&data->location, &flags); 248 249 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 250 251 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 252 pr_err("division of %s by -1 cannot be represented in type %s\n", 253 rhs_val_str, data->type->type_name); 254 else 255 pr_err("division by zero\n"); 256 257 ubsan_epilogue(&flags); 258 } 259 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 260 261 static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 262 { 263 unsigned long flags; 264 265 if (suppress_report(data->location)) 266 return; 267 268 ubsan_prologue(data->location, &flags); 269 270 pr_err("%s null pointer of type %s\n", 271 type_check_kinds[data->type_check_kind], 272 data->type->type_name); 273 274 ubsan_epilogue(&flags); 275 } 276 277 static void handle_misaligned_access(struct type_mismatch_data_common *data, 278 unsigned long ptr) 279 { 280 unsigned long flags; 281 282 if (suppress_report(data->location)) 283 return; 284 285 ubsan_prologue(data->location, &flags); 286 287 pr_err("%s misaligned address %p for type %s\n", 288 type_check_kinds[data->type_check_kind], 289 (void *)ptr, data->type->type_name); 290 pr_err("which requires %ld byte alignment\n", data->alignment); 291 292 ubsan_epilogue(&flags); 293 } 294 295 static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 296 unsigned long ptr) 297 { 298 unsigned long flags; 299 300 if (suppress_report(data->location)) 301 return; 302 303 ubsan_prologue(data->location, &flags); 304 pr_err("%s address %p with insufficient space\n", 305 type_check_kinds[data->type_check_kind], 306 (void *) ptr); 307 pr_err("for an object of type %s\n", data->type->type_name); 308 ubsan_epilogue(&flags); 309 } 310 311 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 312 unsigned long ptr) 313 { 314 315 if (!ptr) 316 handle_null_ptr_deref(data); 317 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 318 handle_misaligned_access(data, ptr); 319 else 320 handle_object_size_mismatch(data, ptr); 321 } 322 323 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 324 void *ptr) 325 { 326 struct type_mismatch_data_common common_data = { 327 .location = &data->location, 328 .type = data->type, 329 .alignment = data->alignment, 330 .type_check_kind = data->type_check_kind 331 }; 332 333 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 334 } 335 EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 336 337 void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data, 338 void *ptr) 339 { 340 341 struct type_mismatch_data_common common_data = { 342 .location = &data->location, 343 .type = data->type, 344 .alignment = 1UL << data->log_alignment, 345 .type_check_kind = data->type_check_kind 346 }; 347 348 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 349 } 350 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 351 352 void __ubsan_handle_vla_bound_not_positive(struct vla_bound_data *data, 353 void *bound) 354 { 355 unsigned long flags; 356 char bound_str[VALUE_LENGTH]; 357 358 if (suppress_report(&data->location)) 359 return; 360 361 ubsan_prologue(&data->location, &flags); 362 363 val_to_string(bound_str, sizeof(bound_str), data->type, bound); 364 pr_err("variable length array bound value %s <= 0\n", bound_str); 365 366 ubsan_epilogue(&flags); 367 } 368 EXPORT_SYMBOL(__ubsan_handle_vla_bound_not_positive); 369 370 void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index) 371 { 372 unsigned long flags; 373 char index_str[VALUE_LENGTH]; 374 375 if (suppress_report(&data->location)) 376 return; 377 378 ubsan_prologue(&data->location, &flags); 379 380 val_to_string(index_str, sizeof(index_str), data->index_type, index); 381 pr_err("index %s is out of range for type %s\n", index_str, 382 data->array_type->type_name); 383 ubsan_epilogue(&flags); 384 } 385 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 386 387 void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data, 388 void *lhs, void *rhs) 389 { 390 unsigned long flags; 391 struct type_descriptor *rhs_type = data->rhs_type; 392 struct type_descriptor *lhs_type = data->lhs_type; 393 char rhs_str[VALUE_LENGTH]; 394 char lhs_str[VALUE_LENGTH]; 395 396 if (suppress_report(&data->location)) 397 return; 398 399 ubsan_prologue(&data->location, &flags); 400 401 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 402 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 403 404 if (val_is_negative(rhs_type, rhs)) 405 pr_err("shift exponent %s is negative\n", rhs_str); 406 407 else if (get_unsigned_val(rhs_type, rhs) >= 408 type_bit_width(lhs_type)) 409 pr_err("shift exponent %s is too large for %u-bit type %s\n", 410 rhs_str, 411 type_bit_width(lhs_type), 412 lhs_type->type_name); 413 else if (val_is_negative(lhs_type, lhs)) 414 pr_err("left shift of negative value %s\n", 415 lhs_str); 416 else 417 pr_err("left shift of %s by %s places cannot be" 418 " represented in type %s\n", 419 lhs_str, rhs_str, 420 lhs_type->type_name); 421 422 ubsan_epilogue(&flags); 423 } 424 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 425 426 427 void __ubsan_handle_builtin_unreachable(struct unreachable_data *data) 428 { 429 unsigned long flags; 430 431 ubsan_prologue(&data->location, &flags); 432 pr_err("calling __builtin_unreachable()\n"); 433 ubsan_epilogue(&flags); 434 panic("can't return from __builtin_unreachable()"); 435 } 436 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 437 438 void __ubsan_handle_load_invalid_value(struct invalid_value_data *data, 439 void *val) 440 { 441 unsigned long flags; 442 char val_str[VALUE_LENGTH]; 443 444 if (suppress_report(&data->location)) 445 return; 446 447 ubsan_prologue(&data->location, &flags); 448 449 val_to_string(val_str, sizeof(val_str), data->type, val); 450 451 pr_err("load of value %s is not a valid value for type %s\n", 452 val_str, data->type->type_name); 453 454 ubsan_epilogue(&flags); 455 } 456 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 457