libsanitizer/asan/asan_errors.cpp

   1 //===-- asan_errors.cpp -----------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file is a part of AddressSanitizer, an address sanity checker.
  10 //
  11 // ASan implementation for error structures.
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "asan_errors.h"
  15 #include "asan_descriptions.h"
  16 #include "asan_mapping.h"
  17 #include "asan_report.h"
  18 #include "asan_stack.h"
  19 #include "sanitizer_common/sanitizer_stackdepot.h"
  20
  21 namespace __asan {
  22
  23 static void OnStackUnwind(const SignalContext &sig,
  24                           const void *callback_context,
  25                           BufferedStackTrace *stack) {
  26   bool fast = common_flags()->fast_unwind_on_fatal;
  27 #if SANITIZER_FREEBSD || SANITIZER_NETBSD
  28   // On FreeBSD the slow unwinding that leverages _Unwind_Backtrace()
  29   // yields the call stack of the signal's handler and not of the code
  30   // that raised the signal (as it does on Linux).
  31   fast = true;
  32 #endif
  33   // Tests and maybe some users expect that scariness is going to be printed
  34   // just before the stack. As only asan has scariness score we have no
  35   // corresponding code in the sanitizer_common and we use this callback to
  36   // print it.
  37   static_cast<const ScarinessScoreBase *>(callback_context)->Print();
  38   stack->Unwind(sig.pc, sig.bp, sig.context, fast);
  39 }
  40
  41 void ErrorDeadlySignal::Print() {
  42   ReportDeadlySignal(signal, tid, &OnStackUnwind, &scariness);
  43 }
  44
  45 void ErrorDoubleFree::Print() {
  46   Decorator d;
  47   Printf("%s", d.Error());
  48   Report(
  49       "ERROR: AddressSanitizer: attempting %s on %p in thread %s:\n",
  50       scariness.GetDescription(), addr_description.addr,
  51       AsanThreadIdAndName(tid).c_str());
  52   Printf("%s", d.Default());
  53   scariness.Print();
  54   GET_STACK_TRACE_FATAL(second_free_stack->trace[0],
  55                         second_free_stack->top_frame_bp);
  56   stack.Print();
  57   addr_description.Print();
  58   ReportErrorSummary(scariness.GetDescription(), &stack);
  59 }
  60
  61 void ErrorNewDeleteTypeMismatch::Print() {
  62   Decorator d;
  63   Printf("%s", d.Error());
  64   Report(
  65       "ERROR: AddressSanitizer: %s on %p in thread %s:\n",
  66       scariness.GetDescription(), addr_description.addr,
  67       AsanThreadIdAndName(tid).c_str());
  68   Printf("%s  object passed to delete has wrong type:\n", d.Default());
  69   if (delete_size != 0) {
  70     Printf(
  71         "  size of the allocated type:   %zd bytes;\n"
  72         "  size of the deallocated type: %zd bytes.\n",
  73         addr_description.chunk_access.chunk_size, delete_size);
  74   }
  75   const uptr user_alignment =
  76       addr_description.chunk_access.user_requested_alignment;
  77   if (delete_alignment != user_alignment) {
  78     char user_alignment_str[32];
  79     char delete_alignment_str[32];
  80     internal_snprintf(user_alignment_str, sizeof(user_alignment_str),
  81                       "%zd bytes", user_alignment);
  82     internal_snprintf(delete_alignment_str, sizeof(delete_alignment_str),
  83                       "%zd bytes", delete_alignment);
  84     static const char *kDefaultAlignment = "default-aligned";
  85     Printf(
  86         "  alignment of the allocated type:   %s;\n"
  87         "  alignment of the deallocated type: %s.\n",
  88         user_alignment > 0 ? user_alignment_str : kDefaultAlignment,
  89         delete_alignment > 0 ? delete_alignment_str : kDefaultAlignment);
  90   }
  91   CHECK_GT(free_stack->size, 0);
  92   scariness.Print();
  93   GET_STACK_TRACE_FATAL(free_stack->trace[0], free_stack->top_frame_bp);
  94   stack.Print();
  95   addr_description.Print();
  96   ReportErrorSummary(scariness.GetDescription(), &stack);
  97   Report(
  98       "HINT: if you don't care about these errors you may set "
  99       "ASAN_OPTIONS=new_delete_type_mismatch=0\n");
 100 }
 101
 102 void ErrorFreeNotMalloced::Print() {
 103   Decorator d;
 104   Printf("%s", d.Error());
 105   Report(
 106       "ERROR: AddressSanitizer: attempting free on address "
 107       "which was not malloc()-ed: %p in thread %s\n",
 108       addr_description.Address(), AsanThreadIdAndName(tid).c_str());
 109   Printf("%s", d.Default());
 110   CHECK_GT(free_stack->size, 0);
 111   scariness.Print();
 112   GET_STACK_TRACE_FATAL(free_stack->trace[0], free_stack->top_frame_bp);
 113   stack.Print();
 114   addr_description.Print();
 115   ReportErrorSummary(scariness.GetDescription(), &stack);
 116 }
 117
 118 void ErrorAllocTypeMismatch::Print() {
 119   static const char *alloc_names[] = {"INVALID", "malloc", "operator new",
 120                                       "operator new []"};
 121   static const char *dealloc_names[] = {"INVALID", "free", "operator delete",
 122                                         "operator delete []"};
 123   CHECK_NE(alloc_type, dealloc_type);
 124   Decorator d;
 125   Printf("%s", d.Error());
 126   Report("ERROR: AddressSanitizer: %s (%s vs %s) on %p\n",
 127          scariness.GetDescription(), alloc_names[alloc_type],
 128          dealloc_names[dealloc_type], addr_description.Address());
 129   Printf("%s", d.Default());
 130   CHECK_GT(dealloc_stack->size, 0);
 131   scariness.Print();
 132   GET_STACK_TRACE_FATAL(dealloc_stack->trace[0], dealloc_stack->top_frame_bp);
 133   stack.Print();
 134   addr_description.Print();
 135   ReportErrorSummary(scariness.GetDescription(), &stack);
 136   Report(
 137       "HINT: if you don't care about these errors you may set "
 138       "ASAN_OPTIONS=alloc_dealloc_mismatch=0\n");
 139 }
 140
 141 void ErrorMallocUsableSizeNotOwned::Print() {
 142   Decorator d;
 143   Printf("%s", d.Error());
 144   Report(
 145       "ERROR: AddressSanitizer: attempting to call malloc_usable_size() for "
 146       "pointer which is not owned: %p\n",
 147       addr_description.Address());
 148   Printf("%s", d.Default());
 149   stack->Print();
 150   addr_description.Print();
 151   ReportErrorSummary(scariness.GetDescription(), stack);
 152 }
 153
 154 void ErrorSanitizerGetAllocatedSizeNotOwned::Print() {
 155   Decorator d;
 156   Printf("%s", d.Error());
 157   Report(
 158       "ERROR: AddressSanitizer: attempting to call "
 159       "__sanitizer_get_allocated_size() for pointer which is not owned: %p\n",
 160       addr_description.Address());
 161   Printf("%s", d.Default());
 162   stack->Print();
 163   addr_description.Print();
 164   ReportErrorSummary(scariness.GetDescription(), stack);
 165 }
 166
 167 void ErrorCallocOverflow::Print() {
 168   Decorator d;
 169   Printf("%s", d.Error());
 170   Report(
 171       "ERROR: AddressSanitizer: calloc parameters overflow: count * size "
 172       "(%zd * %zd) cannot be represented in type size_t (thread %s)\n",
 173       count, size, AsanThreadIdAndName(tid).c_str());
 174   Printf("%s", d.Default());
 175   stack->Print();
 176   PrintHintAllocatorCannotReturnNull();
 177   ReportErrorSummary(scariness.GetDescription(), stack);
 178 }
 179
 180 void ErrorReallocArrayOverflow::Print() {
 181   Decorator d;
 182   Printf("%s", d.Error());
 183   Report(
 184       "ERROR: AddressSanitizer: reallocarray parameters overflow: count * size "
 185       "(%zd * %zd) cannot be represented in type size_t (thread %s)\n",
 186       count, size, AsanThreadIdAndName(tid).c_str());
 187   Printf("%s", d.Default());
 188   stack->Print();
 189   PrintHintAllocatorCannotReturnNull();
 190   ReportErrorSummary(scariness.GetDescription(), stack);
 191 }
 192
 193 void ErrorPvallocOverflow::Print() {
 194   Decorator d;
 195   Printf("%s", d.Error());
 196   Report(
 197       "ERROR: AddressSanitizer: pvalloc parameters overflow: size 0x%zx "
 198       "rounded up to system page size 0x%zx cannot be represented in type "
 199       "size_t (thread %s)\n",
 200       size, GetPageSizeCached(), AsanThreadIdAndName(tid).c_str());
 201   Printf("%s", d.Default());
 202   stack->Print();
 203   PrintHintAllocatorCannotReturnNull();
 204   ReportErrorSummary(scariness.GetDescription(), stack);
 205 }
 206
 207 void ErrorInvalidAllocationAlignment::Print() {
 208   Decorator d;
 209   Printf("%s", d.Error());
 210   Report(
 211       "ERROR: AddressSanitizer: invalid allocation alignment: %zd, "
 212       "alignment must be a power of two (thread %s)\n",
 213       alignment, AsanThreadIdAndName(tid).c_str());
 214   Printf("%s", d.Default());
 215   stack->Print();
 216   PrintHintAllocatorCannotReturnNull();
 217   ReportErrorSummary(scariness.GetDescription(), stack);
 218 }
 219
 220 void ErrorInvalidAlignedAllocAlignment::Print() {
 221   Decorator d;
 222   Printf("%s", d.Error());
 223 #if SANITIZER_POSIX
 224   Report("ERROR: AddressSanitizer: invalid alignment requested in "
 225          "aligned_alloc: %zd, alignment must be a power of two and the "
 226          "requested size 0x%zx must be a multiple of alignment "
 227          "(thread %s)\n", alignment, size, AsanThreadIdAndName(tid).c_str());
 228 #else
 229   Report("ERROR: AddressSanitizer: invalid alignment requested in "
 230          "aligned_alloc: %zd, the requested size 0x%zx must be a multiple of "
 231          "alignment (thread %s)\n", alignment, size,
 232          AsanThreadIdAndName(tid).c_str());
 233 #endif
 234   Printf("%s", d.Default());
 235   stack->Print();
 236   PrintHintAllocatorCannotReturnNull();
 237   ReportErrorSummary(scariness.GetDescription(), stack);
 238 }
 239
 240 void ErrorInvalidPosixMemalignAlignment::Print() {
 241   Decorator d;
 242   Printf("%s", d.Error());
 243   Report(
 244       "ERROR: AddressSanitizer: invalid alignment requested in posix_memalign: "
 245       "%zd, alignment must be a power of two and a multiple of sizeof(void*) "
 246       "== %zd (thread %s)\n",
 247       alignment, sizeof(void*), AsanThreadIdAndName(tid).c_str());  // NOLINT
 248   Printf("%s", d.Default());
 249   stack->Print();
 250   PrintHintAllocatorCannotReturnNull();
 251   ReportErrorSummary(scariness.GetDescription(), stack);
 252 }
 253
 254 void ErrorAllocationSizeTooBig::Print() {
 255   Decorator d;
 256   Printf("%s", d.Error());
 257   Report(
 258       "ERROR: AddressSanitizer: requested allocation size 0x%zx (0x%zx after "
 259       "adjustments for alignment, red zones etc.) exceeds maximum supported "
 260       "size of 0x%zx (thread %s)\n",
 261       user_size, total_size, max_size, AsanThreadIdAndName(tid).c_str());
 262   Printf("%s", d.Default());
 263   stack->Print();
 264   PrintHintAllocatorCannotReturnNull();
 265   ReportErrorSummary(scariness.GetDescription(), stack);
 266 }
 267
 268 void ErrorRssLimitExceeded::Print() {
 269   Decorator d;
 270   Printf("%s", d.Error());
 271   Report(
 272       "ERROR: AddressSanitizer: specified RSS limit exceeded, currently set to "
 273       "soft_rss_limit_mb=%zd\n", common_flags()->soft_rss_limit_mb);
 274   Printf("%s", d.Default());
 275   stack->Print();
 276   PrintHintAllocatorCannotReturnNull();
 277   ReportErrorSummary(scariness.GetDescription(), stack);
 278 }
 279
 280 void ErrorOutOfMemory::Print() {
 281   Decorator d;
 282   Printf("%s", d.Error());
 283   Report(
 284       "ERROR: AddressSanitizer: allocator is out of memory trying to allocate "
 285       "0x%zx bytes\n", requested_size);
 286   Printf("%s", d.Default());
 287   stack->Print();
 288   PrintHintAllocatorCannotReturnNull();
 289   ReportErrorSummary(scariness.GetDescription(), stack);
 290 }
 291
 292 void ErrorStringFunctionMemoryRangesOverlap::Print() {
 293   Decorator d;
 294   char bug_type[100];
 295   internal_snprintf(bug_type, sizeof(bug_type), "%s-param-overlap", function);
 296   Printf("%s", d.Error());
 297   Report(
 298       "ERROR: AddressSanitizer: %s: memory ranges [%p,%p) and [%p, %p) "
 299       "overlap\n",
 300       bug_type, addr1_description.Address(),
 301       addr1_description.Address() + length1, addr2_description.Address(),
 302       addr2_description.Address() + length2);
 303   Printf("%s", d.Default());
 304   scariness.Print();
 305   stack->Print();
 306   addr1_description.Print();
 307   addr2_description.Print();
 308   ReportErrorSummary(bug_type, stack);
 309 }
 310
 311 void ErrorStringFunctionSizeOverflow::Print() {
 312   Decorator d;
 313   Printf("%s", d.Error());
 314   Report("ERROR: AddressSanitizer: %s: (size=%zd)\n",
 315          scariness.GetDescription(), size);
 316   Printf("%s", d.Default());
 317   scariness.Print();
 318   stack->Print();
 319   addr_description.Print();
 320   ReportErrorSummary(scariness.GetDescription(), stack);
 321 }
 322
 323 void ErrorBadParamsToAnnotateContiguousContainer::Print() {
 324   Report(
 325       "ERROR: AddressSanitizer: bad parameters to "
 326       "__sanitizer_annotate_contiguous_container:\n"
 327       "      beg     : %p\n"
 328       "      end     : %p\n"
 329       "      old_mid : %p\n"
 330       "      new_mid : %p\n",
 331       beg, end, old_mid, new_mid);
 332   uptr granularity = SHADOW_GRANULARITY;
 333   if (!IsAligned(beg, granularity))
 334     Report("ERROR: beg is not aligned by %d\n", granularity);
 335   stack->Print();
 336   ReportErrorSummary(scariness.GetDescription(), stack);
 337 }
 338
 339 void ErrorODRViolation::Print() {
 340   Decorator d;
 341   Printf("%s", d.Error());
 342   Report("ERROR: AddressSanitizer: %s (%p):\n", scariness.GetDescription(),
 343          global1.beg);
 344   Printf("%s", d.Default());
 345   InternalScopedString g1_loc(256), g2_loc(256);
 346   PrintGlobalLocation(&g1_loc, global1);
 347   PrintGlobalLocation(&g2_loc, global2);
 348   Printf("  [1] size=%zd '%s' %s\n", global1.size,
 349          MaybeDemangleGlobalName(global1.name), g1_loc.data());
 350   Printf("  [2] size=%zd '%s' %s\n", global2.size,
 351          MaybeDemangleGlobalName(global2.name), g2_loc.data());
 352   if (stack_id1 && stack_id2) {
 353     Printf("These globals were registered at these points:\n");
 354     Printf("  [1]:\n");
 355     StackDepotGet(stack_id1).Print();
 356     Printf("  [2]:\n");
 357     StackDepotGet(stack_id2).Print();
 358   }
 359   Report(
 360       "HINT: if you don't care about these errors you may set "
 361       "ASAN_OPTIONS=detect_odr_violation=0\n");
 362   InternalScopedString error_msg(256);
 363   error_msg.append("%s: global '%s' at %s", scariness.GetDescription(),
 364                    MaybeDemangleGlobalName(global1.name), g1_loc.data());
 365   ReportErrorSummary(error_msg.data());
 366 }
 367
 368 void ErrorInvalidPointerPair::Print() {
 369   Decorator d;
 370   Printf("%s", d.Error());
 371   Report("ERROR: AddressSanitizer: %s: %p %p\n", scariness.GetDescription(),
 372          addr1_description.Address(), addr2_description.Address());
 373   Printf("%s", d.Default());
 374   GET_STACK_TRACE_FATAL(pc, bp);
 375   stack.Print();
 376   addr1_description.Print();
 377   addr2_description.Print();
 378   ReportErrorSummary(scariness.GetDescription(), &stack);
 379 }
 380
 381 static bool AdjacentShadowValuesAreFullyPoisoned(u8 *s) {
 382   return s[-1] > 127 && s[1] > 127;
 383 }
 384
 385 ErrorGeneric::ErrorGeneric(u32 tid, uptr pc_, uptr bp_, uptr sp_, uptr addr,
 386                            bool is_write_, uptr access_size_)
 387     : ErrorBase(tid),
 388       addr_description(addr, access_size_, /*shouldLockThreadRegistry=*/false),
 389       pc(pc_),
 390       bp(bp_),
 391       sp(sp_),
 392       access_size(access_size_),
 393       is_write(is_write_),
 394       shadow_val(0) {
 395   scariness.Clear();
 396   if (access_size) {
 397     if (access_size <= 9) {
 398       char desr[] = "?-byte";
 399       desr[0] = '0' + access_size;
 400       scariness.Scare(access_size + access_size / 2, desr);
 401     } else if (access_size >= 10) {
 402       scariness.Scare(15, "multi-byte");
 403     }
 404     is_write ? scariness.Scare(20, "write") : scariness.Scare(1, "read");
 405
 406     // Determine the error type.
 407     bug_descr = "unknown-crash";
 408     if (AddrIsInMem(addr)) {
 409       u8 *shadow_addr = (u8 *)MemToShadow(addr);
 410       // If we are accessing 16 bytes, look at the second shadow byte.
 411       if (*shadow_addr == 0 && access_size > SHADOW_GRANULARITY) shadow_addr++;
 412       // If we are in the partial right redzone, look at the next shadow byte.
 413       if (*shadow_addr > 0 && *shadow_addr < 128) shadow_addr++;
 414       bool far_from_bounds = false;
 415       shadow_val = *shadow_addr;
 416       int bug_type_score = 0;
 417       // For use-after-frees reads are almost as bad as writes.
 418       int read_after_free_bonus = 0;
 419       switch (shadow_val) {
 420         case kAsanHeapLeftRedzoneMagic:
 421         case kAsanArrayCookieMagic:
 422           bug_descr = "heap-buffer-overflow";
 423           bug_type_score = 10;
 424           far_from_bounds = AdjacentShadowValuesAreFullyPoisoned(shadow_addr);
 425           break;
 426         case kAsanHeapFreeMagic:
 427           bug_descr = "heap-use-after-free";
 428           bug_type_score = 20;
 429           if (!is_write) read_after_free_bonus = 18;
 430           break;
 431         case kAsanStackLeftRedzoneMagic:
 432           bug_descr = "stack-buffer-underflow";
 433           bug_type_score = 25;
 434           far_from_bounds = AdjacentShadowValuesAreFullyPoisoned(shadow_addr);
 435           break;
 436         case kAsanInitializationOrderMagic:
 437           bug_descr = "initialization-order-fiasco";
 438           bug_type_score = 1;
 439           break;
 440         case kAsanStackMidRedzoneMagic:
 441         case kAsanStackRightRedzoneMagic:
 442           bug_descr = "stack-buffer-overflow";
 443           bug_type_score = 25;
 444           far_from_bounds = AdjacentShadowValuesAreFullyPoisoned(shadow_addr);
 445           break;
 446         case kAsanStackAfterReturnMagic:
 447           bug_descr = "stack-use-after-return";
 448           bug_type_score = 30;
 449           if (!is_write) read_after_free_bonus = 18;
 450           break;
 451         case kAsanUserPoisonedMemoryMagic:
 452           bug_descr = "use-after-poison";
 453           bug_type_score = 20;
 454           break;
 455         case kAsanContiguousContainerOOBMagic:
 456           bug_descr = "container-overflow";
 457           bug_type_score = 10;
 458           break;
 459         case kAsanStackUseAfterScopeMagic:
 460           bug_descr = "stack-use-after-scope";
 461           bug_type_score = 10;
 462           break;
 463         case kAsanGlobalRedzoneMagic:
 464           bug_descr = "global-buffer-overflow";
 465           bug_type_score = 10;
 466           far_from_bounds = AdjacentShadowValuesAreFullyPoisoned(shadow_addr);
 467           break;
 468         case kAsanIntraObjectRedzone:
 469           bug_descr = "intra-object-overflow";
 470           bug_type_score = 10;
 471           break;
 472         case kAsanAllocaLeftMagic:
 473         case kAsanAllocaRightMagic:
 474           bug_descr = "dynamic-stack-buffer-overflow";
 475           bug_type_score = 25;
 476           far_from_bounds = AdjacentShadowValuesAreFullyPoisoned(shadow_addr);
 477           break;
 478       }
 479       scariness.Scare(bug_type_score + read_after_free_bonus, bug_descr);
 480       if (far_from_bounds) scariness.Scare(10, "far-from-bounds");
 481     }
 482   }
 483 }
 484
 485 static void PrintContainerOverflowHint() {
 486   Printf("HINT: if you don't care about these errors you may set "
 487          "ASAN_OPTIONS=detect_container_overflow=0.\n"
 488          "If you suspect a false positive see also: "
 489          "https://github.com/google/sanitizers/wiki/"
 490          "AddressSanitizerContainerOverflow.\n");
 491 }
 492
 493 static void PrintShadowByte(InternalScopedString *str, const char *before,
 494     u8 byte, const char *after = "\n") {
 495   PrintMemoryByte(str, before, byte, /*in_shadow*/true, after);
 496 }
 497
 498 static void PrintLegend(InternalScopedString *str) {
 499   str->append(
 500       "Shadow byte legend (one shadow byte represents %d "
 501       "application bytes):\n",
 502       (int)SHADOW_GRANULARITY);
 503   PrintShadowByte(str, "  Addressable:           ", 0);
 504   str->append("  Partially addressable: ");
 505   for (u8 i = 1; i < SHADOW_GRANULARITY; i++) PrintShadowByte(str, "", i, " ");
 506   str->append("\n");
 507   PrintShadowByte(str, "  Heap left redzone:       ",
 508                   kAsanHeapLeftRedzoneMagic);
 509   PrintShadowByte(str, "  Freed heap region:       ", kAsanHeapFreeMagic);
 510   PrintShadowByte(str, "  Stack left redzone:      ",
 511                   kAsanStackLeftRedzoneMagic);
 512   PrintShadowByte(str, "  Stack mid redzone:       ",
 513                   kAsanStackMidRedzoneMagic);
 514   PrintShadowByte(str, "  Stack right redzone:     ",
 515                   kAsanStackRightRedzoneMagic);
 516   PrintShadowByte(str, "  Stack after return:      ",
 517                   kAsanStackAfterReturnMagic);
 518   PrintShadowByte(str, "  Stack use after scope:   ",
 519                   kAsanStackUseAfterScopeMagic);
 520   PrintShadowByte(str, "  Global redzone:          ", kAsanGlobalRedzoneMagic);
 521   PrintShadowByte(str, "  Global init order:       ",
 522                   kAsanInitializationOrderMagic);
 523   PrintShadowByte(str, "  Poisoned by user:        ",
 524                   kAsanUserPoisonedMemoryMagic);
 525   PrintShadowByte(str, "  Container overflow:      ",
 526                   kAsanContiguousContainerOOBMagic);
 527   PrintShadowByte(str, "  Array cookie:            ",
 528                   kAsanArrayCookieMagic);
 529   PrintShadowByte(str, "  Intra object redzone:    ",
 530                   kAsanIntraObjectRedzone);
 531   PrintShadowByte(str, "  ASan internal:           ", kAsanInternalHeapMagic);
 532   PrintShadowByte(str, "  Left alloca redzone:     ", kAsanAllocaLeftMagic);
 533   PrintShadowByte(str, "  Right alloca redzone:    ", kAsanAllocaRightMagic);
 534   PrintShadowByte(str, "  Shadow gap:              ", kAsanShadowGap);
 535 }
 536
 537 static void PrintShadowBytes(InternalScopedString *str, const char *before,
 538                              u8 *bytes, u8 *guilty, uptr n) {
 539   Decorator d;
 540   if (before) str->append("%s%p:", before, bytes);
 541   for (uptr i = 0; i < n; i++) {
 542     u8 *p = bytes + i;
 543     const char *before =
 544         p == guilty ? "[" : (p - 1 == guilty && i != 0) ? "" : " ";
 545     const char *after = p == guilty ? "]" : "";
 546     PrintShadowByte(str, before, *p, after);
 547   }
 548   str->append("\n");
 549 }
 550
 551 static void PrintShadowMemoryForAddress(uptr addr) {
 552   if (!AddrIsInMem(addr)) return;
 553   uptr shadow_addr = MemToShadow(addr);
 554   const uptr n_bytes_per_row = 16;
 555   uptr aligned_shadow = shadow_addr & ~(n_bytes_per_row - 1);
 556   InternalScopedString str(4096 * 8);
 557   str.append("Shadow bytes around the buggy address:\n");
 558   for (int i = -5; i <= 5; i++) {
 559     uptr row_shadow_addr = aligned_shadow + i * n_bytes_per_row;
 560     // Skip rows that would be outside the shadow range. This can happen when
 561     // the user address is near the bottom, top, or shadow gap of the address
 562     // space.
 563     if (!AddrIsInShadow(row_shadow_addr)) continue;
 564     const char *prefix = (i == 0) ? "=>" : "  ";
 565     PrintShadowBytes(&str, prefix, (u8 *)row_shadow_addr, (u8 *)shadow_addr,
 566                      n_bytes_per_row);
 567   }
 568   if (flags()->print_legend) PrintLegend(&str);
 569   Printf("%s", str.data());
 570 }
 571
 572 void ErrorGeneric::Print() {
 573   Decorator d;
 574   Printf("%s", d.Error());
 575   uptr addr = addr_description.Address();
 576   Report("ERROR: AddressSanitizer: %s on address %p at pc %p bp %p sp %p\n",
 577          bug_descr, (void *)addr, pc, bp, sp);
 578   Printf("%s", d.Default());
 579
 580   Printf("%s%s of size %zu at %p thread %s%s\n", d.Access(),
 581          access_size ? (is_write ? "WRITE" : "READ") : "ACCESS", access_size,
 582          (void *)addr, AsanThreadIdAndName(tid).c_str(), d.Default());
 583
 584   scariness.Print();
 585   GET_STACK_TRACE_FATAL(pc, bp);
 586   stack.Print();
 587
 588   // Pass bug_descr because we have a special case for
 589   // initialization-order-fiasco
 590   addr_description.Print(bug_descr);
 591   if (shadow_val == kAsanContiguousContainerOOBMagic)
 592     PrintContainerOverflowHint();
 593   ReportErrorSummary(bug_descr, &stack);
 594   PrintShadowMemoryForAddress(addr);
 595 }
 596
 597 }  // namespace __asan