asan_report.cc revision 58f54555c2528f863e211a0679c2c423cfa55fb2 
1//===-- asan_report.cc ----------------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file is a part of AddressSanitizer, an address sanity checker.
11//
12// This file contains error reporting code.
13//===----------------------------------------------------------------------===//
14#include "asan_flags.h"
15#include "asan_internal.h"
16#include "asan_mapping.h"
17#include "asan_report.h"
18#include "asan_stack.h"
19#include "asan_thread.h"
20#include "asan_thread_registry.h"
21#include "sanitizer_common/sanitizer_common.h"
22#include "sanitizer_common/sanitizer_report_decorator.h"
23
24namespace __asan {
25
26// -------------------- User-specified callbacks ----------------- {{{1
27static void (*error_report_callback)(const char*);
28static char *error_message_buffer = 0;
29static uptr error_message_buffer_pos = 0;
30static uptr error_message_buffer_size = 0;
31
32void AppendToErrorMessageBuffer(const char *buffer) {
33  if (error_message_buffer) {
34    uptr length = internal_strlen(buffer);
35    CHECK_GE(error_message_buffer_size, error_message_buffer_pos);
36    uptr remaining = error_message_buffer_size - error_message_buffer_pos;
37    internal_strncpy(error_message_buffer + error_message_buffer_pos,
38                     buffer, remaining);
39    error_message_buffer[error_message_buffer_size - 1] = '\0';
40    // FIXME: reallocate the buffer instead of truncating the message.
41    error_message_buffer_pos += remaining > length ? length : remaining;
42  }
43}
44
45// ---------------------- Decorator ------------------------------ {{{1
46class Decorator: private __sanitizer::AnsiColorDecorator {
47 public:
48  Decorator() : __sanitizer::AnsiColorDecorator(PrintsToTty()) { }
49  const char *Warning()    { return Red(); }
50  const char *EndWarning() { return Default(); }
51  const char *Access()     { return Blue(); }
52  const char *EndAccess()  { return Default(); }
53  const char *Location()   { return Green(); }
54  const char *EndLocation() { return Default(); }
55  const char *Allocation()  { return Magenta(); }
56  const char *EndAllocation()  { return Default(); }
57};
58
59// ---------------------- Helper functions ----------------------- {{{1
60
61static void PrintBytes(const char *before, uptr *a) {
62  u8 *bytes = (u8*)a;
63  uptr byte_num = (SANITIZER_WORDSIZE) / 8;
64  Printf("%s%p:", before, (void*)a);
65  for (uptr i = 0; i < byte_num; i++) {
66    Printf(" %x%x", bytes[i] >> 4, bytes[i] & 15);
67  }
68  Printf("\n");
69}
70
71static void PrintShadowMemoryForAddress(uptr addr) {
72  if (!AddrIsInMem(addr))
73    return;
74  uptr shadow_addr = MemToShadow(addr);
75  Printf("Shadow byte and word:\n");
76  Printf("  %p: %x\n", (void*)shadow_addr, *(unsigned char*)shadow_addr);
77  uptr aligned_shadow = shadow_addr & ~(kWordSize - 1);
78  PrintBytes("  ", (uptr*)(aligned_shadow));
79  Printf("More shadow bytes:\n");
80  for (int i = -4; i <= 4; i++) {
81    const char *prefix = (i == 0) ? "=>" : "  ";
82    PrintBytes(prefix, (uptr*)(aligned_shadow + i * kWordSize));
83  }
84}
85
86static void PrintZoneForPointer(uptr ptr, uptr zone_ptr,
87                                const char *zone_name) {
88  if (zone_ptr) {
89    if (zone_name) {
90      Printf("malloc_zone_from_ptr(%p) = %p, which is %s\n",
91                 ptr, zone_ptr, zone_name);
92    } else {
93      Printf("malloc_zone_from_ptr(%p) = %p, which doesn't have a name\n",
94                 ptr, zone_ptr);
95    }
96  } else {
97    Printf("malloc_zone_from_ptr(%p) = 0\n", ptr);
98  }
99}
100
101// ---------------------- Address Descriptions ------------------- {{{1
102
103static bool IsASCII(unsigned char c) {
104  return /*0x00 <= c &&*/ c <= 0x7F;
105}
106
107// Check if the global is a zero-terminated ASCII string. If so, print it.
108static void PrintGlobalNameIfASCII(const __asan_global &g) {
109  for (uptr p = g.beg; p < g.beg + g.size - 1; p++) {
110    if (!IsASCII(*(unsigned char*)p)) return;
111  }
112  if (*(char*)(g.beg + g.size - 1) != 0) return;
113  Printf("  '%s' is ascii string '%s'\n", g.name, (char*)g.beg);
114}
115
116bool DescribeAddressRelativeToGlobal(uptr addr, const __asan_global &g) {
117  if (addr < g.beg - kGlobalAndStackRedzone) return false;
118  if (addr >= g.beg + g.size_with_redzone) return false;
119  Decorator d;
120  Printf("%s", d.Location());
121  Printf("%p is located ", (void*)addr);
122  if (addr < g.beg) {
123    Printf("%zd bytes to the left", g.beg - addr);
124  } else if (addr >= g.beg + g.size) {
125    Printf("%zd bytes to the right", addr - (g.beg + g.size));
126  } else {
127    Printf("%zd bytes inside", addr - g.beg);  // Can it happen?
128  }
129  Printf(" of global variable '%s' (0x%zx) of size %zu\n",
130             g.name, g.beg, g.size);
131  Printf("%s", d.EndLocation());
132  PrintGlobalNameIfASCII(g);
133  return true;
134}
135
136bool DescribeAddressIfShadow(uptr addr) {
137  if (AddrIsInMem(addr))
138    return false;
139  static const char kAddrInShadowReport[] =
140      "Address %p is located in the %s.\n";
141  if (AddrIsInShadowGap(addr)) {
142    Printf(kAddrInShadowReport, addr, "shadow gap area");
143    return true;
144  }
145  if (AddrIsInHighShadow(addr)) {
146    Printf(kAddrInShadowReport, addr, "high shadow area");
147    return true;
148  }
149  if (AddrIsInLowShadow(addr)) {
150    Printf(kAddrInShadowReport, addr, "low shadow area");
151    return true;
152  }
153  CHECK(0 && "Address is not in memory and not in shadow?");
154  return false;
155}
156
157bool DescribeAddressIfStack(uptr addr, uptr access_size) {
158  AsanThread *t = asanThreadRegistry().FindThreadByStackAddress(addr);
159  if (!t) return false;
160  const sptr kBufSize = 4095;
161  char buf[kBufSize];
162  uptr offset = 0;
163  const char *frame_descr = t->GetFrameNameByAddr(addr, &offset);
164  // This string is created by the compiler and has the following form:
165  // "FunctioName n alloc_1 alloc_2 ... alloc_n"
166  // where alloc_i looks like "offset size len ObjectName ".
167  CHECK(frame_descr);
168  // Report the function name and the offset.
169  const char *name_end = internal_strchr(frame_descr, ' ');
170  CHECK(name_end);
171  buf[0] = 0;
172  internal_strncat(buf, frame_descr,
173                   Min(kBufSize,
174                       static_cast<sptr>(name_end - frame_descr)));
175  Decorator d;
176  Printf("%s", d.Location());
177  Printf("Address %p is located at offset %zu "
178             "in frame <%s> of T%d's stack:\n",
179             (void*)addr, offset, buf, t->tid());
180  Printf("%s", d.EndLocation());
181  // Report the number of stack objects.
182  char *p;
183  uptr n_objects = internal_simple_strtoll(name_end, &p, 10);
184  CHECK(n_objects > 0);
185  Printf("  This frame has %zu object(s):\n", n_objects);
186  // Report all objects in this frame.
187  for (uptr i = 0; i < n_objects; i++) {
188    uptr beg, size;
189    sptr len;
190    beg  = internal_simple_strtoll(p, &p, 10);
191    size = internal_simple_strtoll(p, &p, 10);
192    len  = internal_simple_strtoll(p, &p, 10);
193    if (beg <= 0 || size <= 0 || len < 0 || *p != ' ') {
194      Printf("AddressSanitizer can't parse the stack frame "
195                 "descriptor: |%s|\n", frame_descr);
196      break;
197    }
198    p++;
199    buf[0] = 0;
200    internal_strncat(buf, p, Min(kBufSize, len));
201    p += len;
202    Printf("    [%zu, %zu) '%s'\n", beg, beg + size, buf);
203  }
204  Printf("HINT: this may be a false positive if your program uses "
205             "some custom stack unwind mechanism or swapcontext\n"
206             "      (longjmp and C++ exceptions *are* supported)\n");
207  DescribeThread(t->summary());
208  return true;
209}
210
211static void DescribeAccessToHeapChunk(AsanChunkView chunk, uptr addr,
212                                      uptr access_size) {
213  uptr offset;
214  Decorator d;
215  Printf("%s", d.Location());
216  Printf("%p is located ", (void*)addr);
217  if (chunk.AddrIsInside(addr, access_size, &offset)) {
218    Printf("%zu bytes inside of", offset);
219  } else if (chunk.AddrIsAtLeft(addr, access_size, &offset)) {
220    Printf("%zu bytes to the left of", offset);
221  } else if (chunk.AddrIsAtRight(addr, access_size, &offset)) {
222    Printf("%zu bytes to the right of", offset);
223  } else {
224    Printf(" somewhere around (this is AddressSanitizer bug!)");
225  }
226  Printf(" %zu-byte region [%p,%p)\n", chunk.UsedSize(),
227         (void*)(chunk.Beg()), (void*)(chunk.End()));
228  Printf("%s", d.EndLocation());
229}
230
231// Return " (thread_name) " or an empty string if the name is empty.
232const char *ThreadNameWithParenthesis(AsanThreadSummary *t, char buff[],
233                                      uptr buff_len) {
234  const char *name = t->name();
235  if (*name == 0) return "";
236  buff[0] = 0;
237  internal_strncat(buff, " (", 3);
238  internal_strncat(buff, name, buff_len - 4);
239  internal_strncat(buff, ")", 2);
240  return buff;
241}
242
243const char *ThreadNameWithParenthesis(u32 tid, char buff[],
244                                      uptr buff_len) {
245  if (tid == kInvalidTid) return "";
246  AsanThreadSummary *t = asanThreadRegistry().FindByTid(tid);
247  return ThreadNameWithParenthesis(t, buff, buff_len);
248}
249
250void DescribeHeapAddress(uptr addr, uptr access_size) {
251  AsanChunkView chunk = FindHeapChunkByAddress(addr);
252  if (!chunk.IsValid()) return;
253  DescribeAccessToHeapChunk(chunk, addr, access_size);
254  CHECK(chunk.AllocTid() != kInvalidTid);
255  AsanThreadSummary *alloc_thread =
256      asanThreadRegistry().FindByTid(chunk.AllocTid());
257  StackTrace alloc_stack;
258  chunk.GetAllocStack(&alloc_stack);
259  AsanThread *t = asanThreadRegistry().GetCurrent();
260  CHECK(t);
261  char tname[128];
262  Decorator d;
263  if (chunk.FreeTid() != kInvalidTid) {
264    AsanThreadSummary *free_thread =
265        asanThreadRegistry().FindByTid(chunk.FreeTid());
266    Printf("%sfreed by thread T%d%s here:%s\n", d.Allocation(),
267           free_thread->tid(),
268           ThreadNameWithParenthesis(free_thread, tname, sizeof(tname)),
269           d.EndAllocation());
270    StackTrace free_stack;
271    chunk.GetFreeStack(&free_stack);
272    PrintStack(&free_stack);
273    Printf("%spreviously allocated by thread T%d%s here:%s\n",
274           d.Allocation(), alloc_thread->tid(),
275           ThreadNameWithParenthesis(alloc_thread, tname, sizeof(tname)),
276           d.EndAllocation());
277    PrintStack(&alloc_stack);
278    DescribeThread(t->summary());
279    DescribeThread(free_thread);
280    DescribeThread(alloc_thread);
281  } else {
282    Printf("%sallocated by thread T%d%s here:%s\n", d.Allocation(),
283           alloc_thread->tid(),
284           ThreadNameWithParenthesis(alloc_thread, tname, sizeof(tname)),
285           d.EndAllocation());
286    PrintStack(&alloc_stack);
287    DescribeThread(t->summary());
288    DescribeThread(alloc_thread);
289  }
290}
291
292void DescribeAddress(uptr addr, uptr access_size) {
293  // Check if this is shadow or shadow gap.
294  if (DescribeAddressIfShadow(addr))
295    return;
296  CHECK(AddrIsInMem(addr));
297  if (DescribeAddressIfGlobal(addr))
298    return;
299  if (DescribeAddressIfStack(addr, access_size))
300    return;
301  // Assume it is a heap address.
302  DescribeHeapAddress(addr, access_size);
303}
304
305// ------------------- Thread description -------------------- {{{1
306
307void DescribeThread(AsanThreadSummary *summary) {
308  CHECK(summary);
309  // No need to announce the main thread.
310  if (summary->tid() == 0 || summary->announced()) {
311    return;
312  }
313  summary->set_announced(true);
314  char tname[128];
315  Printf("Thread T%d%s", summary->tid(),
316         ThreadNameWithParenthesis(summary->tid(), tname, sizeof(tname)));
317  Printf(" created by T%d%s here:\n",
318         summary->parent_tid(),
319         ThreadNameWithParenthesis(summary->parent_tid(),
320                                   tname, sizeof(tname)));
321  PrintStack(summary->stack());
322  // Recursively described parent thread if needed.
323  if (flags()->print_full_thread_history) {
324    AsanThreadSummary *parent_summary =
325        asanThreadRegistry().FindByTid(summary->parent_tid());
326    DescribeThread(parent_summary);
327  }
328}
329
330// -------------------- Different kinds of reports ----------------- {{{1
331
332// Use ScopedInErrorReport to run common actions just before and
333// immediately after printing error report.
334class ScopedInErrorReport {
335 public:
336  ScopedInErrorReport() {
337    static atomic_uint32_t num_calls;
338    static u32 reporting_thread_tid;
339    if (atomic_fetch_add(&num_calls, 1, memory_order_relaxed) != 0) {
340      // Do not print more than one report, otherwise they will mix up.
341      // Error reporting functions shouldn't return at this situation, as
342      // they are defined as no-return.
343      Report("AddressSanitizer: while reporting a bug found another one."
344                 "Ignoring.\n");
345      u32 current_tid = asanThreadRegistry().GetCurrentTidOrInvalid();
346      if (current_tid != reporting_thread_tid) {
347        // ASan found two bugs in different threads simultaneously. Sleep
348        // long enough to make sure that the thread which started to print
349        // an error report will finish doing it.
350        SleepForSeconds(Max(100, flags()->sleep_before_dying + 1));
351      }
352      // If we're still not dead for some reason, use raw Exit() instead of
353      // Die() to bypass any additional checks.
354      Exit(flags()->exitcode);
355    }
356    ASAN_ON_ERROR();
357    reporting_thread_tid = asanThreadRegistry().GetCurrentTidOrInvalid();
358    Printf("===================================================="
359           "=============\n");
360    if (reporting_thread_tid != kInvalidTid) {
361      // We started reporting an error message. Stop using the fake stack
362      // in case we call an instrumented function from a symbolizer.
363      AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
364      CHECK(curr_thread);
365      curr_thread->fake_stack().StopUsingFakeStack();
366    }
367  }
368  // Destructor is NORETURN, as functions that report errors are.
369  NORETURN ~ScopedInErrorReport() {
370    // Make sure the current thread is announced.
371    AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
372    if (curr_thread) {
373      DescribeThread(curr_thread->summary());
374    }
375    // Print memory stats.
376    __asan_print_accumulated_stats();
377    if (error_report_callback) {
378      error_report_callback(error_message_buffer);
379    }
380    Report("ABORTING\n");
381    Die();
382  }
383};
384
385void ReportSIGSEGV(uptr pc, uptr sp, uptr bp, uptr addr) {
386  ScopedInErrorReport in_report;
387  Decorator d;
388  Printf("%s", d.Warning());
389  Report("ERROR: AddressSanitizer: SEGV on unknown address %p"
390             " (pc %p sp %p bp %p T%d)\n",
391             (void*)addr, (void*)pc, (void*)sp, (void*)bp,
392             asanThreadRegistry().GetCurrentTidOrInvalid());
393  Printf("%s", d.EndWarning());
394  Printf("AddressSanitizer can not provide additional info.\n");
395  GET_STACK_TRACE_FATAL(pc, bp);
396  PrintStack(&stack);
397}
398
399void ReportDoubleFree(uptr addr, StackTrace *stack) {
400  ScopedInErrorReport in_report;
401  Decorator d;
402  Printf("%s", d.Warning());
403  Report("ERROR: AddressSanitizer: attempting double-free on %p:\n", addr);
404  Printf("%s", d.EndWarning());
405  PrintStack(stack);
406  DescribeHeapAddress(addr, 1);
407}
408
409void ReportFreeNotMalloced(uptr addr, StackTrace *stack) {
410  ScopedInErrorReport in_report;
411  Decorator d;
412  Printf("%s", d.Warning());
413  Report("ERROR: AddressSanitizer: attempting free on address "
414             "which was not malloc()-ed: %p\n", addr);
415  Printf("%s", d.EndWarning());
416  PrintStack(stack);
417  DescribeHeapAddress(addr, 1);
418}
419
420void ReportMallocUsableSizeNotOwned(uptr addr, StackTrace *stack) {
421  ScopedInErrorReport in_report;
422  Decorator d;
423  Printf("%s", d.Warning());
424  Report("ERROR: AddressSanitizer: attempting to call "
425             "malloc_usable_size() for pointer which is "
426             "not owned: %p\n", addr);
427  Printf("%s", d.EndWarning());
428  PrintStack(stack);
429  DescribeHeapAddress(addr, 1);
430}
431
432void ReportAsanGetAllocatedSizeNotOwned(uptr addr, StackTrace *stack) {
433  ScopedInErrorReport in_report;
434  Decorator d;
435  Printf("%s", d.Warning());
436  Report("ERROR: AddressSanitizer: attempting to call "
437             "__asan_get_allocated_size() for pointer which is "
438             "not owned: %p\n", addr);
439  Printf("%s", d.EndWarning());
440  PrintStack(stack);
441  DescribeHeapAddress(addr, 1);
442}
443
444void ReportStringFunctionMemoryRangesOverlap(
445    const char *function, const char *offset1, uptr length1,
446    const char *offset2, uptr length2, StackTrace *stack) {
447  ScopedInErrorReport in_report;
448  Decorator d;
449  Printf("%s", d.Warning());
450  Report("ERROR: AddressSanitizer: %s-param-overlap: "
451             "memory ranges [%p,%p) and [%p, %p) overlap\n", \
452             function, offset1, offset1 + length1, offset2, offset2 + length2);
453  Printf("%s", d.EndWarning());
454  PrintStack(stack);
455  DescribeAddress((uptr)offset1, length1);
456  DescribeAddress((uptr)offset2, length2);
457}
458
459// ----------------------- Mac-specific reports ----------------- {{{1
460
461void WarnMacFreeUnallocated(
462    uptr addr, uptr zone_ptr, const char *zone_name, StackTrace *stack) {
463  // Just print a warning here.
464  Printf("free_common(%p) -- attempting to free unallocated memory.\n"
465             "AddressSanitizer is ignoring this error on Mac OS now.\n",
466             addr);
467  PrintZoneForPointer(addr, zone_ptr, zone_name);
468  PrintStack(stack);
469  DescribeHeapAddress(addr, 1);
470}
471
472void ReportMacMzReallocUnknown(
473    uptr addr, uptr zone_ptr, const char *zone_name, StackTrace *stack) {
474  ScopedInErrorReport in_report;
475  Printf("mz_realloc(%p) -- attempting to realloc unallocated memory.\n"
476             "This is an unrecoverable problem, exiting now.\n",
477             addr);
478  PrintZoneForPointer(addr, zone_ptr, zone_name);
479  PrintStack(stack);
480  DescribeHeapAddress(addr, 1);
481}
482
483void ReportMacCfReallocUnknown(
484    uptr addr, uptr zone_ptr, const char *zone_name, StackTrace *stack) {
485  ScopedInErrorReport in_report;
486  Printf("cf_realloc(%p) -- attempting to realloc unallocated memory.\n"
487             "This is an unrecoverable problem, exiting now.\n",
488             addr);
489  PrintZoneForPointer(addr, zone_ptr, zone_name);
490  PrintStack(stack);
491  DescribeHeapAddress(addr, 1);
492}
493
494}  // namespace __asan
495
496// --------------------------- Interface --------------------- {{{1
497using namespace __asan;  // NOLINT
498
499void __asan_report_error(uptr pc, uptr bp, uptr sp,
500                         uptr addr, bool is_write, uptr access_size) {
501  ScopedInErrorReport in_report;
502
503  // Determine the error type.
504  const char *bug_descr = "unknown-crash";
505  if (AddrIsInMem(addr)) {
506    u8 *shadow_addr = (u8*)MemToShadow(addr);
507    // If we are accessing 16 bytes, look at the second shadow byte.
508    if (*shadow_addr == 0 && access_size > SHADOW_GRANULARITY)
509      shadow_addr++;
510    // If we are in the partial right redzone, look at the next shadow byte.
511    if (*shadow_addr > 0 && *shadow_addr < 128)
512      shadow_addr++;
513    switch (*shadow_addr) {
514      case kAsanHeapLeftRedzoneMagic:
515      case kAsanHeapRightRedzoneMagic:
516        bug_descr = "heap-buffer-overflow";
517        break;
518      case kAsanHeapFreeMagic:
519        bug_descr = "heap-use-after-free";
520        break;
521      case kAsanStackLeftRedzoneMagic:
522        bug_descr = "stack-buffer-underflow";
523        break;
524      case kAsanInitializationOrderMagic:
525        bug_descr = "initialization-order-fiasco";
526        break;
527      case kAsanStackMidRedzoneMagic:
528      case kAsanStackRightRedzoneMagic:
529      case kAsanStackPartialRedzoneMagic:
530        bug_descr = "stack-buffer-overflow";
531        break;
532      case kAsanStackAfterReturnMagic:
533        bug_descr = "stack-use-after-return";
534        break;
535      case kAsanUserPoisonedMemoryMagic:
536        bug_descr = "use-after-poison";
537        break;
538      case kAsanStackUseAfterScopeMagic:
539        bug_descr = "stack-use-after-scope";
540        break;
541      case kAsanGlobalRedzoneMagic:
542        bug_descr = "global-buffer-overflow";
543        break;
544    }
545  }
546  Decorator d;
547  Printf("%s", d.Warning());
548  Report("ERROR: AddressSanitizer: %s on address "
549             "%p at pc 0x%zx bp 0x%zx sp 0x%zx\n",
550             bug_descr, (void*)addr, pc, bp, sp);
551  Printf("%s", d.EndWarning());
552
553  u32 curr_tid = asanThreadRegistry().GetCurrentTidOrInvalid();
554  char tname[128];
555  Printf("%s%s of size %zu at %p thread T%d%s%s\n",
556         d.Access(),
557         access_size ? (is_write ? "WRITE" : "READ") : "ACCESS",
558         access_size, (void*)addr, curr_tid,
559         ThreadNameWithParenthesis(curr_tid, tname, sizeof(tname)),
560         d.EndAccess());
561
562  GET_STACK_TRACE_FATAL(pc, bp);
563  PrintStack(&stack);
564
565  DescribeAddress(addr, access_size);
566
567  PrintShadowMemoryForAddress(addr);
568}
569
570void NOINLINE __asan_set_error_report_callback(void (*callback)(const char*)) {
571  error_report_callback = callback;
572  if (callback) {
573    error_message_buffer_size = 1 << 16;
574    error_message_buffer =
575        (char*)MmapOrDie(error_message_buffer_size, __FUNCTION__);
576    error_message_buffer_pos = 0;
577  }
578}
579
580#if !SANITIZER_SUPPORTS_WEAK_HOOKS
581// Provide default implementation of __asan_on_error that does nothing
582// and may be overriden by user.
583SANITIZER_WEAK_ATTRIBUTE SANITIZER_INTERFACE_ATTRIBUTE NOINLINE
584void __asan_on_error() {}
585#endif
586