asan_report.cc revision cb9bd24e5f226b9a922098403cbd1589be39e605 
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
22namespace __asan {
23
24// -------------------- User-specified callbacks ----------------- {{{1
25static void (*error_report_callback)(const char*);
26static char *error_message_buffer = 0;
27static uptr error_message_buffer_pos = 0;
28static uptr error_message_buffer_size = 0;
29
30void AppendToErrorMessageBuffer(const char *buffer) {
31  if (error_message_buffer) {
32    uptr length = internal_strlen(buffer);
33    CHECK_GE(error_message_buffer_size, error_message_buffer_pos);
34    uptr remaining = error_message_buffer_size - error_message_buffer_pos;
35    internal_strncpy(error_message_buffer + error_message_buffer_pos,
36                     buffer, remaining);
37    error_message_buffer[error_message_buffer_size - 1] = '\0';
38    // FIXME: reallocate the buffer instead of truncating the message.
39    error_message_buffer_pos += remaining > length ? length : remaining;
40  }
41}
42
43static void (*on_error_callback)(void);
44
45// ---------------------- Helper functions ----------------------- {{{1
46
47static void PrintBytes(const char *before, uptr *a) {
48  u8 *bytes = (u8*)a;
49  uptr byte_num = (__WORDSIZE) / 8;
50  Printf("%s%p:", before, (void*)a);
51  for (uptr i = 0; i < byte_num; i++) {
52    Printf(" %x%x", bytes[i] >> 4, bytes[i] & 15);
53  }
54  Printf("\n");
55}
56
57static void PrintShadowMemoryForAddress(uptr addr) {
58  if (!AddrIsInMem(addr))
59    return;
60  uptr shadow_addr = MemToShadow(addr);
61  Printf("Shadow byte and word:\n");
62  Printf("  %p: %x\n", (void*)shadow_addr, *(unsigned char*)shadow_addr);
63  uptr aligned_shadow = shadow_addr & ~(kWordSize - 1);
64  PrintBytes("  ", (uptr*)(aligned_shadow));
65  Printf("More shadow bytes:\n");
66  for (int i = -4; i <= 4; i++) {
67    const char *prefix = (i == 0) ? "=>" : "  ";
68    PrintBytes(prefix, (uptr*)(aligned_shadow + i * kWordSize));
69  }
70}
71
72static void PrintZoneForPointer(uptr ptr, uptr zone_ptr,
73                                const char *zone_name) {
74  if (zone_ptr) {
75    if (zone_name) {
76      Printf("malloc_zone_from_ptr(%p) = %p, which is %s\n",
77                 ptr, zone_ptr, zone_name);
78    } else {
79      Printf("malloc_zone_from_ptr(%p) = %p, which doesn't have a name\n",
80                 ptr, zone_ptr);
81    }
82  } else {
83    Printf("malloc_zone_from_ptr(%p) = 0\n", ptr);
84  }
85}
86
87// ---------------------- Address Descriptions ------------------- {{{1
88
89static bool IsASCII(unsigned char c) {
90  return /*0x00 <= c &&*/ c <= 0x7F;
91}
92
93// Check if the global is a zero-terminated ASCII string. If so, print it.
94static void PrintGlobalNameIfASCII(const __asan_global &g) {
95  for (uptr p = g.beg; p < g.beg + g.size - 1; p++) {
96    if (!IsASCII(*(unsigned char*)p)) return;
97  }
98  if (*(char*)(g.beg + g.size - 1) != 0) return;
99  Printf("  '%s' is ascii string '%s'\n", g.name, (char*)g.beg);
100}
101
102bool DescribeAddressRelativeToGlobal(uptr addr, const __asan_global &g) {
103  if (addr < g.beg - kGlobalAndStackRedzone) return false;
104  if (addr >= g.beg + g.size_with_redzone) return false;
105  Printf("%p is located ", (void*)addr);
106  if (addr < g.beg) {
107    Printf("%zd bytes to the left", g.beg - addr);
108  } else if (addr >= g.beg + g.size) {
109    Printf("%zd bytes to the right", addr - (g.beg + g.size));
110  } else {
111    Printf("%zd bytes inside", addr - g.beg);  // Can it happen?
112  }
113  Printf(" of global variable '%s' (0x%zx) of size %zu\n",
114             g.name, g.beg, g.size);
115  PrintGlobalNameIfASCII(g);
116  return true;
117}
118
119bool DescribeAddressIfShadow(uptr addr) {
120  if (AddrIsInMem(addr))
121    return false;
122  static const char kAddrInShadowReport[] =
123      "Address %p is located in the %s.\n";
124  if (AddrIsInShadowGap(addr)) {
125    Printf(kAddrInShadowReport, addr, "shadow gap area");
126    return true;
127  }
128  if (AddrIsInHighShadow(addr)) {
129    Printf(kAddrInShadowReport, addr, "high shadow area");
130    return true;
131  }
132  if (AddrIsInLowShadow(addr)) {
133    Printf(kAddrInShadowReport, addr, "low shadow area");
134    return true;
135  }
136  CHECK(0 && "Address is not in memory and not in shadow?");
137  return false;
138}
139
140bool DescribeAddressIfStack(uptr addr, uptr access_size) {
141  AsanThread *t = asanThreadRegistry().FindThreadByStackAddress(addr);
142  if (!t) return false;
143  const sptr kBufSize = 4095;
144  char buf[kBufSize];
145  uptr offset = 0;
146  const char *frame_descr = t->GetFrameNameByAddr(addr, &offset);
147  // This string is created by the compiler and has the following form:
148  // "FunctioName n alloc_1 alloc_2 ... alloc_n"
149  // where alloc_i looks like "offset size len ObjectName ".
150  CHECK(frame_descr);
151  // Report the function name and the offset.
152  const char *name_end = internal_strchr(frame_descr, ' ');
153  CHECK(name_end);
154  buf[0] = 0;
155  internal_strncat(buf, frame_descr,
156                   Min(kBufSize,
157                       static_cast<sptr>(name_end - frame_descr)));
158  Printf("Address %p is located at offset %zu "
159             "in frame <%s> of T%d's stack:\n",
160             (void*)addr, offset, buf, t->tid());
161  // Report the number of stack objects.
162  char *p;
163  uptr n_objects = internal_simple_strtoll(name_end, &p, 10);
164  CHECK(n_objects > 0);
165  Printf("  This frame has %zu object(s):\n", n_objects);
166  // Report all objects in this frame.
167  for (uptr i = 0; i < n_objects; i++) {
168    uptr beg, size;
169    sptr len;
170    beg  = internal_simple_strtoll(p, &p, 10);
171    size = internal_simple_strtoll(p, &p, 10);
172    len  = internal_simple_strtoll(p, &p, 10);
173    if (beg <= 0 || size <= 0 || len < 0 || *p != ' ') {
174      Printf("AddressSanitizer can't parse the stack frame "
175                 "descriptor: |%s|\n", frame_descr);
176      break;
177    }
178    p++;
179    buf[0] = 0;
180    internal_strncat(buf, p, Min(kBufSize, len));
181    p += len;
182    Printf("    [%zu, %zu) '%s'\n", beg, beg + size, buf);
183  }
184  Printf("HINT: this may be a false positive if your program uses "
185             "some custom stack unwind mechanism\n"
186             "      (longjmp and C++ exceptions *are* supported)\n");
187  DescribeThread(t->summary());
188  return true;
189}
190
191void DescribeAddress(uptr addr, uptr access_size) {
192  // Check if this is shadow or shadow gap.
193  if (DescribeAddressIfShadow(addr))
194    return;
195  CHECK(AddrIsInMem(addr));
196  if (DescribeAddressIfGlobal(addr))
197    return;
198  if (DescribeAddressIfStack(addr, access_size))
199    return;
200  // Assume it is a heap address.
201  DescribeHeapAddress(addr, access_size);
202}
203
204// ------------------- Thread description -------------------- {{{1
205
206void DescribeThread(AsanThreadSummary *summary) {
207  CHECK(summary);
208  // No need to announce the main thread.
209  if (summary->tid() == 0 || summary->announced()) {
210    return;
211  }
212  summary->set_announced(true);
213  Printf("Thread T%d created by T%d here:\n",
214         summary->tid(), summary->parent_tid());
215  PrintStack(summary->stack());
216  // Recursively described parent thread if needed.
217  if (flags()->print_full_thread_history) {
218    AsanThreadSummary *parent_summary =
219        asanThreadRegistry().FindByTid(summary->parent_tid());
220    DescribeThread(parent_summary);
221  }
222}
223
224// -------------------- Different kinds of reports ----------------- {{{1
225
226// Use ScopedInErrorReport to run common actions just before and
227// immediately after printing error report.
228class ScopedInErrorReport {
229 public:
230  ScopedInErrorReport() {
231    static atomic_uint32_t num_calls;
232    if (atomic_fetch_add(&num_calls, 1, memory_order_relaxed) != 0) {
233      // Do not print more than one report, otherwise they will mix up.
234      // Error reporting functions shouldn't return at this situation, as
235      // they are defined as no-return.
236      Report("AddressSanitizer: while reporting a bug found another one."
237                 "Ignoring.\n");
238      // We can't use infinite busy loop here, as ASan may try to report an
239      // error while another error report is being printed (e.g. if the code
240      // that prints error report for buffer overflow results in SEGV).
241      SleepForSeconds(Max(5, flags()->sleep_before_dying + 1));
242      Die();
243    }
244    if (on_error_callback) {
245      on_error_callback();
246    }
247    Printf("===================================================="
248               "=============\n");
249    AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
250    if (curr_thread) {
251      // We started reporting an error message. Stop using the fake stack
252      // in case we call an instrumented function from a symbolizer.
253      curr_thread->fake_stack().StopUsingFakeStack();
254    }
255  }
256  // Destructor is NORETURN, as functions that report errors are.
257  NORETURN ~ScopedInErrorReport() {
258    // Make sure the current thread is announced.
259    AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
260    if (curr_thread) {
261      DescribeThread(curr_thread->summary());
262    }
263    // Print memory stats.
264    __asan_print_accumulated_stats();
265    if (error_report_callback) {
266      error_report_callback(error_message_buffer);
267    }
268    Report("ABORTING\n");
269    Die();
270  }
271};
272
273void ReportSIGSEGV(uptr pc, uptr sp, uptr bp, uptr addr) {
274  ScopedInErrorReport in_report;
275  Report("ERROR: AddressSanitizer crashed on unknown address %p"
276             " (pc %p sp %p bp %p T%d)\n",
277             (void*)addr, (void*)pc, (void*)sp, (void*)bp,
278             asanThreadRegistry().GetCurrentTidOrInvalid());
279  Printf("AddressSanitizer can not provide additional info.\n");
280  GET_STACK_TRACE_WITH_PC_AND_BP(kStackTraceMax, pc, bp);
281  PrintStack(&stack);
282}
283
284void ReportDoubleFree(uptr addr, StackTrace *stack) {
285  ScopedInErrorReport in_report;
286  Report("ERROR: AddressSanitizer attempting double-free on %p:\n", addr);
287  PrintStack(stack);
288  DescribeHeapAddress(addr, 1);
289}
290
291void ReportFreeNotMalloced(uptr addr, StackTrace *stack) {
292  ScopedInErrorReport in_report;
293  Report("ERROR: AddressSanitizer attempting free on address "
294             "which was not malloc()-ed: %p\n", addr);
295  PrintStack(stack);
296  DescribeHeapAddress(addr, 1);
297}
298
299void ReportMallocUsableSizeNotOwned(uptr addr, StackTrace *stack) {
300  ScopedInErrorReport in_report;
301  Report("ERROR: AddressSanitizer attempting to call "
302             "malloc_usable_size() for pointer which is "
303             "not owned: %p\n", addr);
304  PrintStack(stack);
305  DescribeHeapAddress(addr, 1);
306}
307
308void ReportAsanGetAllocatedSizeNotOwned(uptr addr, StackTrace *stack) {
309  ScopedInErrorReport in_report;
310  Report("ERROR: AddressSanitizer attempting to call "
311             "__asan_get_allocated_size() for pointer which is "
312             "not owned: %p\n", addr);
313  PrintStack(stack);
314  DescribeHeapAddress(addr, 1);
315}
316
317void ReportStringFunctionMemoryRangesOverlap(
318    const char *function, const char *offset1, uptr length1,
319    const char *offset2, uptr length2, StackTrace *stack) {
320  ScopedInErrorReport in_report;
321  Report("ERROR: AddressSanitizer %s-param-overlap: "
322             "memory ranges [%p,%p) and [%p, %p) overlap\n", \
323             function, offset1, offset1 + length1, offset2, offset2 + length2);
324  PrintStack(stack);
325  DescribeAddress((uptr)offset1, length1);
326  DescribeAddress((uptr)offset2, length2);
327}
328
329// ----------------------- Mac-specific reports ----------------- {{{1
330
331void WarnMacFreeUnallocated(
332    uptr addr, uptr zone_ptr, const char *zone_name, StackTrace *stack) {
333  // Just print a warning here.
334  Printf("free_common(%p) -- attempting to free unallocated memory.\n"
335             "AddressSanitizer is ignoring this error on Mac OS now.\n",
336             addr);
337  PrintZoneForPointer(addr, zone_ptr, zone_name);
338  PrintStack(stack);
339  DescribeHeapAddress(addr, 1);
340}
341
342void ReportMacMzReallocUnknown(
343    uptr addr, uptr zone_ptr, const char *zone_name, StackTrace *stack) {
344  ScopedInErrorReport in_report;
345  Printf("mz_realloc(%p) -- attempting to realloc unallocated memory.\n"
346             "This is an unrecoverable problem, exiting now.\n",
347             addr);
348  PrintZoneForPointer(addr, zone_ptr, zone_name);
349  PrintStack(stack);
350  DescribeHeapAddress(addr, 1);
351}
352
353void ReportMacCfReallocUnknown(
354    uptr addr, uptr zone_ptr, const char *zone_name, StackTrace *stack) {
355  ScopedInErrorReport in_report;
356  Printf("cf_realloc(%p) -- attempting to realloc unallocated memory.\n"
357             "This is an unrecoverable problem, exiting now.\n",
358             addr);
359  PrintZoneForPointer(addr, zone_ptr, zone_name);
360  PrintStack(stack);
361  DescribeHeapAddress(addr, 1);
362}
363
364}  // namespace __asan
365
366// --------------------------- Interface --------------------- {{{1
367using namespace __asan;  // NOLINT
368
369void __asan_report_error(uptr pc, uptr bp, uptr sp,
370                         uptr addr, bool is_write, uptr access_size) {
371  ScopedInErrorReport in_report;
372
373  // Determine the error type.
374  const char *bug_descr = "unknown-crash";
375  if (AddrIsInMem(addr)) {
376    u8 *shadow_addr = (u8*)MemToShadow(addr);
377    // If we are accessing 16 bytes, look at the second shadow byte.
378    if (*shadow_addr == 0 && access_size > SHADOW_GRANULARITY)
379      shadow_addr++;
380    // If we are in the partial right redzone, look at the next shadow byte.
381    if (*shadow_addr > 0 && *shadow_addr < 128)
382      shadow_addr++;
383    switch (*shadow_addr) {
384      case kAsanHeapLeftRedzoneMagic:
385      case kAsanHeapRightRedzoneMagic:
386        bug_descr = "heap-buffer-overflow";
387        break;
388      case kAsanHeapFreeMagic:
389        bug_descr = "heap-use-after-free";
390        break;
391      case kAsanStackLeftRedzoneMagic:
392        bug_descr = "stack-buffer-underflow";
393        break;
394      case kAsanInitializationOrderMagic:
395        bug_descr = "initialization-order-fiasco";
396        break;
397      case kAsanStackMidRedzoneMagic:
398      case kAsanStackRightRedzoneMagic:
399      case kAsanStackPartialRedzoneMagic:
400        bug_descr = "stack-buffer-overflow";
401        break;
402      case kAsanStackAfterReturnMagic:
403        bug_descr = "stack-use-after-return";
404        break;
405      case kAsanUserPoisonedMemoryMagic:
406        bug_descr = "use-after-poison";
407        break;
408      case kAsanGlobalRedzoneMagic:
409        bug_descr = "global-buffer-overflow";
410        break;
411    }
412  }
413
414  Report("ERROR: AddressSanitizer %s on address "
415             "%p at pc 0x%zx bp 0x%zx sp 0x%zx\n",
416             bug_descr, (void*)addr, pc, bp, sp);
417
418  u32 curr_tid = asanThreadRegistry().GetCurrentTidOrInvalid();
419  Printf("%s of size %zu at %p thread T%d\n",
420             access_size ? (is_write ? "WRITE" : "READ") : "ACCESS",
421             access_size, (void*)addr, curr_tid);
422
423  GET_STACK_TRACE_WITH_PC_AND_BP(kStackTraceMax, pc, bp);
424  PrintStack(&stack);
425
426  DescribeAddress(addr, access_size);
427
428  PrintShadowMemoryForAddress(addr);
429}
430
431void NOINLINE __asan_set_error_report_callback(void (*callback)(const char*)) {
432  error_report_callback = callback;
433  if (callback) {
434    error_message_buffer_size = 1 << 16;
435    error_message_buffer =
436        (char*)MmapOrDie(error_message_buffer_size, __FUNCTION__);
437    error_message_buffer_pos = 0;
438  }
439}
440
441void NOINLINE __asan_set_on_error_callback(void (*callback)(void)) {
442  on_error_callback = callback;
443}
444