asan_rtl.cc revision e218beb2d14b663bd277158f386a86d0e62fef74 
1//===-- asan_rtl.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// Main file of the ASan run-time library.
13//===----------------------------------------------------------------------===//
14#include "asan_allocator.h"
15#include "asan_interceptors.h"
16#include "asan_interface.h"
17#include "asan_internal.h"
18#include "asan_lock.h"
19#include "asan_mapping.h"
20#include "asan_report.h"
21#include "asan_stack.h"
22#include "asan_stats.h"
23#include "asan_thread.h"
24#include "asan_thread_registry.h"
25#include "sanitizer_common/sanitizer_atomic.h"
26#include "sanitizer_common/sanitizer_flags.h"
27#include "sanitizer_common/sanitizer_libc.h"
28
29namespace __sanitizer {
30using namespace __asan;
31
32void Die() {
33  static atomic_uint32_t num_calls;
34  if (atomic_fetch_add(&num_calls, 1, memory_order_relaxed) != 0) {
35    // Don't die twice - run a busy loop.
36    while (1) { }
37  }
38  if (flags()->sleep_before_dying) {
39    Report("Sleeping for %d second(s)\n", flags()->sleep_before_dying);
40    SleepForSeconds(flags()->sleep_before_dying);
41  }
42  if (flags()->unmap_shadow_on_exit)
43    UnmapOrDie((void*)kLowShadowBeg, kHighShadowEnd - kLowShadowBeg);
44  if (death_callback)
45    death_callback();
46  if (flags()->abort_on_error)
47    Abort();
48  Exit(flags()->exitcode);
49}
50
51void CheckFailed(const char *file, int line, const char *cond, u64 v1, u64 v2) {
52  AsanReport("AddressSanitizer CHECK failed: %s:%d \"%s\" (0x%zx, 0x%zx)\n",
53             file, line, cond, (uptr)v1, (uptr)v2);
54  PRINT_CURRENT_STACK();
55  ShowStatsAndAbort();
56}
57
58}  // namespace __sanitizer
59
60namespace __asan {
61
62// -------------------------- Flags ------------------------- {{{1
63static const int kMallocContextSize = 30;
64
65static Flags asan_flags;
66
67Flags *flags() {
68  return &asan_flags;
69}
70
71static void ParseFlagsFromString(Flags *f, const char *str) {
72  ParseFlag(str, &f->quarantine_size, "quarantine_size");
73  ParseFlag(str, &f->symbolize, "symbolize");
74  ParseFlag(str, &f->verbosity, "verbosity");
75  ParseFlag(str, &f->redzone, "redzone");
76  CHECK(f->redzone >= 16);
77  CHECK(IsPowerOfTwo(f->redzone));
78
79  ParseFlag(str, &f->debug, "debug");
80  ParseFlag(str, &f->report_globals, "report_globals");
81  ParseFlag(str, &f->malloc_context_size, "malloc_context_size");
82  CHECK(f->malloc_context_size <= kMallocContextSize);
83
84  ParseFlag(str, &f->replace_str, "replace_str");
85  ParseFlag(str, &f->replace_intrin, "replace_intrin");
86  ParseFlag(str, &f->replace_cfallocator, "replace_cfallocator");
87  ParseFlag(str, &f->mac_ignore_invalid_free, "mac_ignore_invalid_free");
88  ParseFlag(str, &f->use_fake_stack, "use_fake_stack");
89  ParseFlag(str, &f->max_malloc_fill_size, "max_malloc_fill_size");
90  ParseFlag(str, &f->exitcode, "exitcode");
91  ParseFlag(str, &f->allow_user_poisoning, "allow_user_poisoning");
92  ParseFlag(str, &f->sleep_before_dying, "sleep_before_dying");
93  ParseFlag(str, &f->handle_segv, "handle_segv");
94  ParseFlag(str, &f->use_sigaltstack, "use_sigaltstack");
95  ParseFlag(str, &f->check_malloc_usable_size, "check_malloc_usable_size");
96  ParseFlag(str, &f->unmap_shadow_on_exit, "unmap_shadow_on_exit");
97  ParseFlag(str, &f->abort_on_error, "abort_on_error");
98  ParseFlag(str, &f->atexit, "atexit");
99  ParseFlag(str, &f->disable_core, "disable_core");
100  ParseFlag(str, &f->strip_path_prefix, "strip_path_prefix");
101}
102
103extern "C" {
104const char* WEAK __asan_default_options() { return ""; }
105}  // extern "C"
106
107void InitializeFlags(Flags *f, const char *env) {
108  internal_memset(f, 0, sizeof(*f));
109
110  f->quarantine_size = (ASAN_LOW_MEMORY) ? 1UL << 24 : 1UL << 28;
111  f->symbolize = false;
112  f->verbosity = 0;
113  f->redzone = (ASAN_LOW_MEMORY) ? 64 : 128;
114  f->debug = false;
115  f->report_globals = 1;
116  f->malloc_context_size = kMallocContextSize;
117  f->replace_str = true;
118  f->replace_intrin = true;
119  f->replace_cfallocator = true;
120  f->mac_ignore_invalid_free = false;
121  f->use_fake_stack = true;
122  f->max_malloc_fill_size = 0;
123  f->exitcode = ASAN_DEFAULT_FAILURE_EXITCODE;
124  f->allow_user_poisoning = true;
125  f->sleep_before_dying = 0;
126  f->handle_segv = ASAN_NEEDS_SEGV;
127  f->use_sigaltstack = false;
128  f->check_malloc_usable_size = true;
129  f->unmap_shadow_on_exit = false;
130  f->abort_on_error = false;
131  f->atexit = false;
132  f->disable_core = (__WORDSIZE == 64);
133  f->strip_path_prefix = "";
134
135  // Override from user-specified string.
136  ParseFlagsFromString(f, __asan_default_options());
137  if (flags()->verbosity) {
138    Report("Using the defaults from __asan_default_options: %s\n",
139           __asan_default_options());
140  }
141
142  // Override from command line.
143  ParseFlagsFromString(f, env);
144}
145
146// -------------------------- Globals --------------------- {{{1
147int asan_inited;
148bool asan_init_is_running;
149void (*death_callback)(void);
150static void (*error_report_callback)(const char*);
151char *error_message_buffer = 0;
152uptr error_message_buffer_pos = 0;
153uptr error_message_buffer_size = 0;
154
155// -------------------------- Misc ---------------- {{{1
156void ShowStatsAndAbort() {
157  __asan_print_accumulated_stats();
158  Die();
159}
160
161static void PrintBytes(const char *before, uptr *a) {
162  u8 *bytes = (u8*)a;
163  uptr byte_num = (__WORDSIZE) / 8;
164  AsanPrintf("%s%p:", before, (void*)a);
165  for (uptr i = 0; i < byte_num; i++) {
166    AsanPrintf(" %x%x", bytes[i] >> 4, bytes[i] & 15);
167  }
168  AsanPrintf("\n");
169}
170
171void AppendToErrorMessageBuffer(const char *buffer) {
172  if (error_message_buffer) {
173    uptr length = internal_strlen(buffer);
174    CHECK_GE(error_message_buffer_size, error_message_buffer_pos);
175    uptr remaining = error_message_buffer_size - error_message_buffer_pos;
176    internal_strncpy(error_message_buffer + error_message_buffer_pos,
177                     buffer, remaining);
178    error_message_buffer[error_message_buffer_size - 1] = '\0';
179    // FIXME: reallocate the buffer instead of truncating the message.
180    error_message_buffer_pos += remaining > length ? length : remaining;
181  }
182}
183
184// ---------------------- mmap -------------------- {{{1
185// Reserve memory range [beg, end].
186static void ReserveShadowMemoryRange(uptr beg, uptr end) {
187  CHECK((beg % kPageSize) == 0);
188  CHECK(((end + 1) % kPageSize) == 0);
189  uptr size = end - beg + 1;
190  void *res = MmapFixedNoReserve(beg, size);
191  CHECK(res == (void*)beg && "ReserveShadowMemoryRange failed");
192}
193
194// ---------------------- LowLevelAllocator ------------- {{{1
195void *LowLevelAllocator::Allocate(uptr size) {
196  CHECK((size & (size - 1)) == 0 && "size must be a power of two");
197  if (allocated_end_ - allocated_current_ < (sptr)size) {
198    uptr size_to_allocate = Max(size, kPageSize);
199    allocated_current_ =
200        (char*)MmapOrDie(size_to_allocate, __FUNCTION__);
201    allocated_end_ = allocated_current_ + size_to_allocate;
202    PoisonShadow((uptr)allocated_current_, size_to_allocate,
203                 kAsanInternalHeapMagic);
204  }
205  CHECK(allocated_end_ - allocated_current_ >= (sptr)size);
206  void *res = allocated_current_;
207  allocated_current_ += size;
208  return res;
209}
210
211// -------------------------- Run-time entry ------------------- {{{1
212// exported functions
213#define ASAN_REPORT_ERROR(type, is_write, size)                     \
214extern "C" NOINLINE INTERFACE_ATTRIBUTE                        \
215void __asan_report_ ## type ## size(uptr addr);                \
216void __asan_report_ ## type ## size(uptr addr) {               \
217  GET_CALLER_PC_BP_SP;                                              \
218  __asan_report_error(pc, bp, sp, addr, is_write, size);            \
219}
220
221ASAN_REPORT_ERROR(load, false, 1)
222ASAN_REPORT_ERROR(load, false, 2)
223ASAN_REPORT_ERROR(load, false, 4)
224ASAN_REPORT_ERROR(load, false, 8)
225ASAN_REPORT_ERROR(load, false, 16)
226ASAN_REPORT_ERROR(store, true, 1)
227ASAN_REPORT_ERROR(store, true, 2)
228ASAN_REPORT_ERROR(store, true, 4)
229ASAN_REPORT_ERROR(store, true, 8)
230ASAN_REPORT_ERROR(store, true, 16)
231
232// Force the linker to keep the symbols for various ASan interface functions.
233// We want to keep those in the executable in order to let the instrumented
234// dynamic libraries access the symbol even if it is not used by the executable
235// itself. This should help if the build system is removing dead code at link
236// time.
237static NOINLINE void force_interface_symbols() {
238  volatile int fake_condition = 0;  // prevent dead condition elimination.
239  if (fake_condition) {
240    __asan_report_load1(0);
241    __asan_report_load2(0);
242    __asan_report_load4(0);
243    __asan_report_load8(0);
244    __asan_report_load16(0);
245    __asan_report_store1(0);
246    __asan_report_store2(0);
247    __asan_report_store4(0);
248    __asan_report_store8(0);
249    __asan_report_store16(0);
250    __asan_register_global(0, 0, 0);
251    __asan_register_globals(0, 0);
252    __asan_unregister_globals(0, 0);
253    __asan_set_death_callback(0);
254    __asan_set_error_report_callback(0);
255    __asan_handle_no_return();
256  }
257}
258
259// -------------------------- Init ------------------- {{{1
260static void asan_atexit() {
261  AsanPrintf("AddressSanitizer exit stats:\n");
262  __asan_print_accumulated_stats();
263}
264
265}  // namespace __asan
266
267// ---------------------- Interface ---------------- {{{1
268using namespace __asan;  // NOLINT
269
270int __asan_set_error_exit_code(int exit_code) {
271  int old = flags()->exitcode;
272  flags()->exitcode = exit_code;
273  return old;
274}
275
276void NOINLINE __asan_handle_no_return() {
277  int local_stack;
278  AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
279  CHECK(curr_thread);
280  uptr top = curr_thread->stack_top();
281  uptr bottom = ((uptr)&local_stack - kPageSize) & ~(kPageSize-1);
282  PoisonShadow(bottom, top - bottom, 0);
283}
284
285void NOINLINE __asan_set_death_callback(void (*callback)(void)) {
286  death_callback = callback;
287}
288
289void NOINLINE __asan_set_error_report_callback(void (*callback)(const char*)) {
290  error_report_callback = callback;
291  if (callback) {
292    error_message_buffer_size = 1 << 16;
293    error_message_buffer =
294        (char*)MmapOrDie(error_message_buffer_size, __FUNCTION__);
295    error_message_buffer_pos = 0;
296  }
297}
298
299void __asan_report_error(uptr pc, uptr bp, uptr sp,
300                         uptr addr, bool is_write, uptr access_size) {
301  static atomic_uint32_t num_calls;
302  if (atomic_fetch_add(&num_calls, 1, memory_order_relaxed) != 0) {
303    // Do not print more than one report, otherwise they will mix up.
304    // We can not return here because the function is marked as never-return.
305    AsanPrintf("AddressSanitizer: while reporting a bug found another one."
306               "Ignoring.\n");
307    SleepForSeconds(5);
308    Die();
309  }
310
311  AsanPrintf("===================================================="
312             "=============\n");
313  const char *bug_descr = "unknown-crash";
314  if (AddrIsInMem(addr)) {
315    u8 *shadow_addr = (u8*)MemToShadow(addr);
316    // If we are accessing 16 bytes, look at the second shadow byte.
317    if (*shadow_addr == 0 && access_size > SHADOW_GRANULARITY)
318      shadow_addr++;
319    // If we are in the partial right redzone, look at the next shadow byte.
320    if (*shadow_addr > 0 && *shadow_addr < 128)
321      shadow_addr++;
322    switch (*shadow_addr) {
323      case kAsanHeapLeftRedzoneMagic:
324      case kAsanHeapRightRedzoneMagic:
325        bug_descr = "heap-buffer-overflow";
326        break;
327      case kAsanHeapFreeMagic:
328        bug_descr = "heap-use-after-free";
329        break;
330      case kAsanStackLeftRedzoneMagic:
331        bug_descr = "stack-buffer-underflow";
332        break;
333      case kAsanStackMidRedzoneMagic:
334      case kAsanStackRightRedzoneMagic:
335      case kAsanStackPartialRedzoneMagic:
336        bug_descr = "stack-buffer-overflow";
337        break;
338      case kAsanStackAfterReturnMagic:
339        bug_descr = "stack-use-after-return";
340        break;
341      case kAsanUserPoisonedMemoryMagic:
342        bug_descr = "use-after-poison";
343        break;
344      case kAsanGlobalRedzoneMagic:
345        bug_descr = "global-buffer-overflow";
346        break;
347    }
348  }
349
350  AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
351  u32 curr_tid = asanThreadRegistry().GetCurrentTidOrInvalid();
352
353  if (curr_thread) {
354    // We started reporting an error message. Stop using the fake stack
355    // in case we will call an instrumented function from a symbolizer.
356    curr_thread->fake_stack().StopUsingFakeStack();
357  }
358
359  AsanReport("ERROR: AddressSanitizer %s on address "
360             "%p at pc 0x%zx bp 0x%zx sp 0x%zx\n",
361             bug_descr, (void*)addr, pc, bp, sp);
362
363  AsanPrintf("%s of size %zu at %p thread T%d\n",
364             access_size ? (is_write ? "WRITE" : "READ") : "ACCESS",
365             access_size, (void*)addr, curr_tid);
366
367  if (flags()->debug) {
368    PrintBytes("PC: ", (uptr*)pc);
369  }
370
371  GET_STACK_TRACE_WITH_PC_AND_BP(kStackTraceMax, pc, bp);
372  stack.PrintStack();
373
374  DescribeAddress(addr, access_size);
375
376  if (AddrIsInMem(addr)) {
377    uptr shadow_addr = MemToShadow(addr);
378    AsanReport("ABORTING\n");
379    __asan_print_accumulated_stats();
380    AsanPrintf("Shadow byte and word:\n");
381    AsanPrintf("  %p: %x\n", (void*)shadow_addr, *(unsigned char*)shadow_addr);
382    uptr aligned_shadow = shadow_addr & ~(kWordSize - 1);
383    PrintBytes("  ", (uptr*)(aligned_shadow));
384    AsanPrintf("More shadow bytes:\n");
385    PrintBytes("  ", (uptr*)(aligned_shadow-4*kWordSize));
386    PrintBytes("  ", (uptr*)(aligned_shadow-3*kWordSize));
387    PrintBytes("  ", (uptr*)(aligned_shadow-2*kWordSize));
388    PrintBytes("  ", (uptr*)(aligned_shadow-1*kWordSize));
389    PrintBytes("=>", (uptr*)(aligned_shadow+0*kWordSize));
390    PrintBytes("  ", (uptr*)(aligned_shadow+1*kWordSize));
391    PrintBytes("  ", (uptr*)(aligned_shadow+2*kWordSize));
392    PrintBytes("  ", (uptr*)(aligned_shadow+3*kWordSize));
393    PrintBytes("  ", (uptr*)(aligned_shadow+4*kWordSize));
394  }
395  if (error_report_callback) {
396    error_report_callback(error_message_buffer);
397  }
398  Die();
399}
400
401
402void __asan_init() {
403  if (asan_inited) return;
404  asan_init_is_running = true;
405
406  // Make sure we are not statically linked.
407  AsanDoesNotSupportStaticLinkage();
408
409  // Initialize flags.
410  const char *options = GetEnv("ASAN_OPTIONS");
411  InitializeFlags(flags(), options);
412
413  if (flags()->verbosity && options) {
414    Report("Parsed ASAN_OPTIONS: %s\n", options);
415  }
416
417  if (flags()->atexit) {
418    Atexit(asan_atexit);
419  }
420
421  // interceptors
422  InitializeAsanInterceptors();
423
424  ReplaceSystemMalloc();
425  ReplaceOperatorsNewAndDelete();
426
427  if (flags()->verbosity) {
428    Printf("|| `[%p, %p]` || HighMem    ||\n",
429           (void*)kHighMemBeg, (void*)kHighMemEnd);
430    Printf("|| `[%p, %p]` || HighShadow ||\n",
431           (void*)kHighShadowBeg, (void*)kHighShadowEnd);
432    Printf("|| `[%p, %p]` || ShadowGap  ||\n",
433           (void*)kShadowGapBeg, (void*)kShadowGapEnd);
434    Printf("|| `[%p, %p]` || LowShadow  ||\n",
435           (void*)kLowShadowBeg, (void*)kLowShadowEnd);
436    Printf("|| `[%p, %p]` || LowMem     ||\n",
437           (void*)kLowMemBeg, (void*)kLowMemEnd);
438    Printf("MemToShadow(shadow): %p %p %p %p\n",
439           (void*)MEM_TO_SHADOW(kLowShadowBeg),
440           (void*)MEM_TO_SHADOW(kLowShadowEnd),
441           (void*)MEM_TO_SHADOW(kHighShadowBeg),
442           (void*)MEM_TO_SHADOW(kHighShadowEnd));
443    Printf("red_zone=%zu\n", (uptr)flags()->redzone);
444    Printf("malloc_context_size=%zu\n", (uptr)flags()->malloc_context_size);
445
446    Printf("SHADOW_SCALE: %zx\n", (uptr)SHADOW_SCALE);
447    Printf("SHADOW_GRANULARITY: %zx\n", (uptr)SHADOW_GRANULARITY);
448    Printf("SHADOW_OFFSET: %zx\n", (uptr)SHADOW_OFFSET);
449    CHECK(SHADOW_SCALE >= 3 && SHADOW_SCALE <= 7);
450  }
451
452  if (flags()->disable_core) {
453    DisableCoreDumper();
454  }
455
456  uptr shadow_start = kLowShadowBeg;
457  if (kLowShadowBeg > 0) shadow_start -= kMmapGranularity;
458  uptr shadow_end = kHighShadowEnd;
459  if (MemoryRangeIsAvailable(shadow_start, shadow_end)) {
460    if (kLowShadowBeg != kLowShadowEnd) {
461      // mmap the low shadow plus at least one page.
462      ReserveShadowMemoryRange(kLowShadowBeg - kMmapGranularity, kLowShadowEnd);
463    }
464    // mmap the high shadow.
465    ReserveShadowMemoryRange(kHighShadowBeg, kHighShadowEnd);
466    // protect the gap
467    void *prot = Mprotect(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
468    CHECK(prot == (void*)kShadowGapBeg);
469  } else {
470    Report("Shadow memory range interleaves with an existing memory mapping. "
471           "ASan cannot proceed correctly. ABORTING.\n");
472    DumpProcessMap();
473    Die();
474  }
475
476  InstallSignalHandlers();
477
478  // On Linux AsanThread::ThreadStart() calls malloc() that's why asan_inited
479  // should be set to 1 prior to initializing the threads.
480  asan_inited = 1;
481  asan_init_is_running = false;
482
483  asanThreadRegistry().Init();
484  asanThreadRegistry().GetMain()->ThreadStart();
485  force_interface_symbols();  // no-op.
486
487  if (flags()->verbosity) {
488    Report("AddressSanitizer Init done\n");
489  }
490}
491
492#if defined(ASAN_USE_PREINIT_ARRAY)
493  // On Linux, we force __asan_init to be called before anyone else
494  // by placing it into .preinit_array section.
495  // FIXME: do we have anything like this on Mac?
496  __attribute__((section(".preinit_array")))
497    typeof(__asan_init) *__asan_preinit =__asan_init;
498#elif defined(_WIN32) && defined(_DLL)
499  // On Windows, when using dynamic CRT (/MD), we can put a pointer
500  // to __asan_init into the global list of C initializers.
501  // See crt0dat.c in the CRT sources for the details.
502  #pragma section(".CRT$XIB", long, read)  // NOLINT
503  __declspec(allocate(".CRT$XIB")) void (*__asan_preinit)() = __asan_init;
504#endif
505