libsanitizer/asan/asan_errors.cc

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