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 <ryabinin.a.a@gmail.com> 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#include <linux/ubsan.h> 18#include <kunit/test-bug.h> 19 20#include "ubsan.h" 21 22#ifdef CONFIG_UBSAN_TRAP 23/* 24 * Only include matches for UBSAN checks that are actually compiled in. 25 * The mappings of struct SanitizerKind (the -fsanitize=xxx args) to 26 * enum SanitizerHandler (the traps) in Clang is in clang/lib/CodeGen/. 27 */ 28const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type) 29{ 30 switch (check_type) { 31#ifdef CONFIG_UBSAN_BOUNDS 32 /* 33 * SanitizerKind::ArrayBounds and SanitizerKind::LocalBounds 34 * emit SanitizerHandler::OutOfBounds. 35 */ 36 case ubsan_out_of_bounds: 37 return "UBSAN: array index out of bounds"; 38#endif 39#ifdef CONFIG_UBSAN_SHIFT 40 /* 41 * SanitizerKind::ShiftBase and SanitizerKind::ShiftExponent 42 * emit SanitizerHandler::ShiftOutOfBounds. 43 */ 44 case ubsan_shift_out_of_bounds: 45 return "UBSAN: shift out of bounds"; 46#endif 47#if defined(CONFIG_UBSAN_DIV_ZERO) || defined(CONFIG_UBSAN_SIGNED_WRAP) 48 /* 49 * SanitizerKind::IntegerDivideByZero and 50 * SanitizerKind::SignedIntegerOverflow emit 51 * SanitizerHandler::DivremOverflow. 52 */ 53 case ubsan_divrem_overflow: 54 return "UBSAN: divide/remainder overflow"; 55#endif 56#ifdef CONFIG_UBSAN_UNREACHABLE 57 /* 58 * SanitizerKind::Unreachable emits 59 * SanitizerHandler::BuiltinUnreachable. 60 */ 61 case ubsan_builtin_unreachable: 62 return "UBSAN: unreachable code"; 63#endif 64#if defined(CONFIG_UBSAN_BOOL) || defined(CONFIG_UBSAN_ENUM) 65 /* 66 * SanitizerKind::Bool and SanitizerKind::Enum emit 67 * SanitizerHandler::LoadInvalidValue. 68 */ 69 case ubsan_load_invalid_value: 70 return "UBSAN: loading invalid value"; 71#endif 72#ifdef CONFIG_UBSAN_ALIGNMENT 73 /* 74 * SanitizerKind::Alignment emits SanitizerHandler::TypeMismatch 75 * or SanitizerHandler::AlignmentAssumption. 76 */ 77 case ubsan_alignment_assumption: 78 return "UBSAN: alignment assumption"; 79 case ubsan_type_mismatch: 80 return "UBSAN: type mismatch"; 81#endif 82#ifdef CONFIG_UBSAN_SIGNED_WRAP 83 /* 84 * SanitizerKind::SignedIntegerOverflow emits 85 * SanitizerHandler::AddOverflow, SanitizerHandler::SubOverflow, 86 * or SanitizerHandler::MulOverflow. 87 */ 88 case ubsan_add_overflow: 89 return "UBSAN: integer addition overflow"; 90 case ubsan_sub_overflow: 91 return "UBSAN: integer subtraction overflow"; 92 case ubsan_mul_overflow: 93 return "UBSAN: integer multiplication overflow"; 94#endif 95 default: 96 return "UBSAN: unrecognized failure code"; 97 } 98} 99 100#else 101static const char * const type_check_kinds[] = { 102 "load of", 103 "store to", 104 "reference binding to", 105 "member access within", 106 "member call on", 107 "constructor call on", 108 "downcast of", 109 "downcast of" 110}; 111 112#define REPORTED_BIT 31 113 114#if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN) 115#define COLUMN_MASK (~(1U << REPORTED_BIT)) 116#define LINE_MASK (~0U) 117#else 118#define COLUMN_MASK (~0U) 119#define LINE_MASK (~(1U << REPORTED_BIT)) 120#endif 121 122#define VALUE_LENGTH 40 123 124static bool was_reported(struct source_location *location) 125{ 126 return test_and_set_bit(REPORTED_BIT, &location->reported); 127} 128 129static bool suppress_report(struct source_location *loc) 130{ 131 return current->in_ubsan || was_reported(loc); 132} 133 134static bool type_is_int(struct type_descriptor *type) 135{ 136 return type->type_kind == type_kind_int; 137} 138 139static bool type_is_signed(struct type_descriptor *type) 140{ 141 WARN_ON(!type_is_int(type)); 142 return type->type_info & 1; 143} 144 145static unsigned type_bit_width(struct type_descriptor *type) 146{ 147 return 1 << (type->type_info >> 1); 148} 149 150static bool is_inline_int(struct type_descriptor *type) 151{ 152 unsigned inline_bits = sizeof(unsigned long)*8; 153 unsigned bits = type_bit_width(type); 154 155 WARN_ON(!type_is_int(type)); 156 157 return bits <= inline_bits; 158} 159 160static s_max get_signed_val(struct type_descriptor *type, void *val) 161{ 162 if (is_inline_int(type)) { 163 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type); 164 unsigned long ulong_val = (unsigned long)val; 165 166 return ((s_max)ulong_val) << extra_bits >> extra_bits; 167 } 168 169 if (type_bit_width(type) == 64) 170 return *(s64 *)val; 171 172 return *(s_max *)val; 173} 174 175static bool val_is_negative(struct type_descriptor *type, void *val) 176{ 177 return type_is_signed(type) && get_signed_val(type, val) < 0; 178} 179 180static u_max get_unsigned_val(struct type_descriptor *type, void *val) 181{ 182 if (is_inline_int(type)) 183 return (unsigned long)val; 184 185 if (type_bit_width(type) == 64) 186 return *(u64 *)val; 187 188 return *(u_max *)val; 189} 190 191static void val_to_string(char *str, size_t size, struct type_descriptor *type, 192 void *value) 193{ 194 if (type_is_int(type)) { 195 if (type_bit_width(type) == 128) { 196#if defined(CONFIG_ARCH_SUPPORTS_INT128) 197 u_max val = get_unsigned_val(type, value); 198 199 scnprintf(str, size, "0x%08x%08x%08x%08x", 200 (u32)(val >> 96), 201 (u32)(val >> 64), 202 (u32)(val >> 32), 203 (u32)(val)); 204#else 205 WARN_ON(1); 206#endif 207 } else if (type_is_signed(type)) { 208 scnprintf(str, size, "%lld", 209 (s64)get_signed_val(type, value)); 210 } else { 211 scnprintf(str, size, "%llu", 212 (u64)get_unsigned_val(type, value)); 213 } 214 } 215} 216 217static void ubsan_prologue(struct source_location *loc, const char *reason) 218{ 219 current->in_ubsan++; 220 221 pr_warn(CUT_HERE); 222 223 pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name, 224 loc->line & LINE_MASK, loc->column & COLUMN_MASK); 225 226 kunit_fail_current_test("%s in %s", reason, loc->file_name); 227} 228 229static void ubsan_epilogue(void) 230{ 231 dump_stack(); 232 pr_warn("---[ end trace ]---\n"); 233 234 current->in_ubsan--; 235 236 check_panic_on_warn("UBSAN"); 237} 238 239static void handle_overflow(struct overflow_data *data, void *lhs, 240 void *rhs, char op) 241{ 242 243 struct type_descriptor *type = data->type; 244 char lhs_val_str[VALUE_LENGTH]; 245 char rhs_val_str[VALUE_LENGTH]; 246 247 if (suppress_report(&data->location)) 248 return; 249 250 ubsan_prologue(&data->location, type_is_signed(type) ? 251 "signed-integer-overflow" : 252 "unsigned-integer-overflow"); 253 254 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs); 255 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs); 256 pr_err("%s %c %s cannot be represented in type %s\n", 257 lhs_val_str, 258 op, 259 rhs_val_str, 260 type->type_name); 261 262 ubsan_epilogue(); 263} 264 265void __ubsan_handle_add_overflow(void *data, 266 void *lhs, void *rhs) 267{ 268 269 handle_overflow(data, lhs, rhs, '+'); 270} 271EXPORT_SYMBOL(__ubsan_handle_add_overflow); 272 273void __ubsan_handle_sub_overflow(void *data, 274 void *lhs, void *rhs) 275{ 276 handle_overflow(data, lhs, rhs, '-'); 277} 278EXPORT_SYMBOL(__ubsan_handle_sub_overflow); 279 280void __ubsan_handle_mul_overflow(void *data, 281 void *lhs, void *rhs) 282{ 283 handle_overflow(data, lhs, rhs, '*'); 284} 285EXPORT_SYMBOL(__ubsan_handle_mul_overflow); 286 287void __ubsan_handle_negate_overflow(void *_data, void *old_val) 288{ 289 struct overflow_data *data = _data; 290 char old_val_str[VALUE_LENGTH]; 291 292 if (suppress_report(&data->location)) 293 return; 294 295 ubsan_prologue(&data->location, "negation-overflow"); 296 297 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); 298 299 pr_err("negation of %s cannot be represented in type %s:\n", 300 old_val_str, data->type->type_name); 301 302 ubsan_epilogue(); 303} 304EXPORT_SYMBOL(__ubsan_handle_negate_overflow); 305 306 307void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs) 308{ 309 struct overflow_data *data = _data; 310 char rhs_val_str[VALUE_LENGTH]; 311 312 if (suppress_report(&data->location)) 313 return; 314 315 ubsan_prologue(&data->location, "division-overflow"); 316 317 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); 318 319 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1) 320 pr_err("division of %s by -1 cannot be represented in type %s\n", 321 rhs_val_str, data->type->type_name); 322 else 323 pr_err("division by zero\n"); 324 325 ubsan_epilogue(); 326} 327EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); 328 329static void handle_null_ptr_deref(struct type_mismatch_data_common *data) 330{ 331 if (suppress_report(data->location)) 332 return; 333 334 ubsan_prologue(data->location, "null-ptr-deref"); 335 336 pr_err("%s null pointer of type %s\n", 337 type_check_kinds[data->type_check_kind], 338 data->type->type_name); 339 340 ubsan_epilogue(); 341} 342 343static void handle_misaligned_access(struct type_mismatch_data_common *data, 344 unsigned long ptr) 345{ 346 if (suppress_report(data->location)) 347 return; 348 349 ubsan_prologue(data->location, "misaligned-access"); 350 351 pr_err("%s misaligned address %p for type %s\n", 352 type_check_kinds[data->type_check_kind], 353 (void *)ptr, data->type->type_name); 354 pr_err("which requires %ld byte alignment\n", data->alignment); 355 356 ubsan_epilogue(); 357} 358 359static void handle_object_size_mismatch(struct type_mismatch_data_common *data, 360 unsigned long ptr) 361{ 362 if (suppress_report(data->location)) 363 return; 364 365 ubsan_prologue(data->location, "object-size-mismatch"); 366 pr_err("%s address %p with insufficient space\n", 367 type_check_kinds[data->type_check_kind], 368 (void *) ptr); 369 pr_err("for an object of type %s\n", data->type->type_name); 370 ubsan_epilogue(); 371} 372 373static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, 374 unsigned long ptr) 375{ 376 unsigned long flags = user_access_save(); 377 378 if (!ptr) 379 handle_null_ptr_deref(data); 380 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) 381 handle_misaligned_access(data, ptr); 382 else 383 handle_object_size_mismatch(data, ptr); 384 385 user_access_restore(flags); 386} 387 388void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, 389 void *ptr) 390{ 391 struct type_mismatch_data_common common_data = { 392 .location = &data->location, 393 .type = data->type, 394 .alignment = data->alignment, 395 .type_check_kind = data->type_check_kind 396 }; 397 398 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 399} 400EXPORT_SYMBOL(__ubsan_handle_type_mismatch); 401 402void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr) 403{ 404 struct type_mismatch_data_v1 *data = _data; 405 struct type_mismatch_data_common common_data = { 406 .location = &data->location, 407 .type = data->type, 408 .alignment = 1UL << data->log_alignment, 409 .type_check_kind = data->type_check_kind 410 }; 411 412 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr); 413} 414EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); 415 416void __ubsan_handle_out_of_bounds(void *_data, void *index) 417{ 418 struct out_of_bounds_data *data = _data; 419 char index_str[VALUE_LENGTH]; 420 421 if (suppress_report(&data->location)) 422 return; 423 424 ubsan_prologue(&data->location, "array-index-out-of-bounds"); 425 426 val_to_string(index_str, sizeof(index_str), data->index_type, index); 427 pr_err("index %s is out of range for type %s\n", index_str, 428 data->array_type->type_name); 429 ubsan_epilogue(); 430} 431EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); 432 433void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs) 434{ 435 struct shift_out_of_bounds_data *data = _data; 436 struct type_descriptor *rhs_type = data->rhs_type; 437 struct type_descriptor *lhs_type = data->lhs_type; 438 char rhs_str[VALUE_LENGTH]; 439 char lhs_str[VALUE_LENGTH]; 440 unsigned long ua_flags = user_access_save(); 441 442 if (suppress_report(&data->location)) 443 goto out; 444 445 ubsan_prologue(&data->location, "shift-out-of-bounds"); 446 447 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); 448 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); 449 450 if (val_is_negative(rhs_type, rhs)) 451 pr_err("shift exponent %s is negative\n", rhs_str); 452 453 else if (get_unsigned_val(rhs_type, rhs) >= 454 type_bit_width(lhs_type)) 455 pr_err("shift exponent %s is too large for %u-bit type %s\n", 456 rhs_str, 457 type_bit_width(lhs_type), 458 lhs_type->type_name); 459 else if (val_is_negative(lhs_type, lhs)) 460 pr_err("left shift of negative value %s\n", 461 lhs_str); 462 else 463 pr_err("left shift of %s by %s places cannot be" 464 " represented in type %s\n", 465 lhs_str, rhs_str, 466 lhs_type->type_name); 467 468 ubsan_epilogue(); 469out: 470 user_access_restore(ua_flags); 471} 472EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); 473 474 475void __ubsan_handle_builtin_unreachable(void *_data) 476{ 477 struct unreachable_data *data = _data; 478 ubsan_prologue(&data->location, "unreachable"); 479 pr_err("calling __builtin_unreachable()\n"); 480 ubsan_epilogue(); 481 panic("can't return from __builtin_unreachable()"); 482} 483EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); 484 485void __ubsan_handle_load_invalid_value(void *_data, void *val) 486{ 487 struct invalid_value_data *data = _data; 488 char val_str[VALUE_LENGTH]; 489 unsigned long ua_flags = user_access_save(); 490 491 if (suppress_report(&data->location)) 492 goto out; 493 494 ubsan_prologue(&data->location, "invalid-load"); 495 496 val_to_string(val_str, sizeof(val_str), data->type, val); 497 498 pr_err("load of value %s is not a valid value for type %s\n", 499 val_str, data->type->type_name); 500 501 ubsan_epilogue(); 502out: 503 user_access_restore(ua_flags); 504} 505EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); 506 507void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr, 508 unsigned long align, 509 unsigned long offset) 510{ 511 struct alignment_assumption_data *data = _data; 512 unsigned long real_ptr; 513 514 if (suppress_report(&data->location)) 515 return; 516 517 ubsan_prologue(&data->location, "alignment-assumption"); 518 519 if (offset) 520 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed", 521 align, offset, data->type->type_name); 522 else 523 pr_err("assumption of %lu byte alignment for pointer of type %s failed", 524 align, data->type->type_name); 525 526 real_ptr = ptr - offset; 527 pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes", 528 offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0), 529 real_ptr & (align - 1)); 530 531 ubsan_epilogue(); 532} 533EXPORT_SYMBOL(__ubsan_handle_alignment_assumption); 534 535#endif /* !CONFIG_UBSAN_TRAP */ 536