asan_rtl.cc revision f03d8afc8b8dd072c4e2884a7475ee28ac5f3f41 
1//===-- asan_rtl.cc ---------------------------------------------*- C++ -*-===//
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_stack.h"
21#include "asan_stats.h"
22#include "asan_thread.h"
23#include "asan_thread_registry.h"
24
25namespace __asan {
26
27// -------------------------- Flags ------------------------- {{{1
28static const size_t kMallocContextSize = 30;
29static int    FLAG_atexit;
30
31size_t FLAG_redzone;  // power of two, >= 32
32size_t FLAG_quarantine_size;
33int    FLAG_demangle;
34bool   FLAG_symbolize;
35int    FLAG_v;
36int    FLAG_debug;
37bool   FLAG_poison_shadow;
38int    FLAG_report_globals;
39size_t FLAG_malloc_context_size = kMallocContextSize;
40uintptr_t FLAG_large_malloc;
41bool   FLAG_handle_segv;
42bool   FLAG_use_sigaltstack;
43bool   FLAG_replace_str;
44bool   FLAG_replace_intrin;
45bool   FLAG_replace_cfallocator;  // Used on Mac only.
46size_t FLAG_max_malloc_fill_size = 0;
47bool   FLAG_use_fake_stack;
48int    FLAG_exitcode = ASAN_DEFAULT_FAILURE_EXITCODE;
49bool   FLAG_allow_user_poisoning;
50int    FLAG_sleep_before_dying;
51
52// -------------------------- Globals --------------------- {{{1
53int asan_inited;
54bool asan_init_is_running;
55static void (*death_callback)(void);
56static void (*error_report_callback)(const char*);
57char *error_message_buffer = NULL;
58size_t error_message_buffer_pos = 0;
59size_t error_message_buffer_size = 0;
60
61// -------------------------- Misc ---------------- {{{1
62void ShowStatsAndAbort() {
63  __asan_print_accumulated_stats();
64  AsanDie();
65}
66
67static void PrintBytes(const char *before, uintptr_t *a) {
68  uint8_t *bytes = (uint8_t*)a;
69  size_t byte_num = (__WORDSIZE) / 8;
70  Printf("%s%p:", before, (void*)a);
71  for (size_t i = 0; i < byte_num; i++) {
72    Printf(" %x%x", bytes[i] >> 4, bytes[i] & 15);
73  }
74  Printf("\n");
75}
76
77size_t ReadFileToBuffer(const char *file_name, char **buff,
78                         size_t *buff_size, size_t max_len) {
79  const size_t kMinFileLen = kPageSize;
80  size_t read_len = 0;
81  *buff = 0;
82  *buff_size = 0;
83  // The files we usually open are not seekable, so try different buffer sizes.
84  for (size_t size = kMinFileLen; size <= max_len; size *= 2) {
85    int fd = AsanOpenReadonly(file_name);
86    if (fd < 0) return -1;
87    AsanUnmapOrDie(*buff, *buff_size);
88    *buff = (char*)AsanMmapSomewhereOrDie(size, __FUNCTION__);
89    *buff_size = size;
90    // Read up to one page at a time.
91    read_len = 0;
92    bool reached_eof = false;
93    while (read_len + kPageSize <= size) {
94      size_t just_read = AsanRead(fd, *buff + read_len, kPageSize);
95      if (just_read == 0) {
96        reached_eof = true;
97        break;
98      }
99      read_len += just_read;
100    }
101    AsanClose(fd);
102    if (reached_eof)  // We've read the whole file.
103      break;
104  }
105  return read_len;
106}
107
108void AsanDie() {
109  static int num_calls = 0;
110  if (AtomicInc(&num_calls) > 1) {
111    // Don't die twice - run a busy loop.
112    while (1) { }
113  }
114  if (FLAG_sleep_before_dying) {
115    Report("Sleeping for %d second(s)\n", FLAG_sleep_before_dying);
116    SleepForSeconds(FLAG_sleep_before_dying);
117  }
118  if (death_callback)
119    death_callback();
120  Exit(FLAG_exitcode);
121}
122
123// ---------------------- mmap -------------------- {{{1
124void OutOfMemoryMessageAndDie(const char *mem_type, size_t size) {
125  Report("ERROR: AddressSanitizer failed to allocate "
126         "0x%zx (%zd) bytes of %s\n",
127         size, size, mem_type);
128  PRINT_CURRENT_STACK();
129  ShowStatsAndAbort();
130}
131
132// Reserve memory range [beg, end].
133static void ReserveShadowMemoryRange(uintptr_t beg, uintptr_t end) {
134  CHECK((beg % kPageSize) == 0);
135  CHECK(((end + 1) % kPageSize) == 0);
136  size_t size = end - beg + 1;
137  void *res = AsanMmapFixedNoReserve(beg, size);
138  CHECK(res == (void*)beg && "ReserveShadowMemoryRange failed");
139}
140
141// ---------------------- LowLevelAllocator ------------- {{{1
142void *LowLevelAllocator::Allocate(size_t size) {
143  CHECK((size & (size - 1)) == 0 && "size must be a power of two");
144  if (allocated_end_ - allocated_current_ < size) {
145    size_t size_to_allocate = Max(size, kPageSize);
146    allocated_current_ =
147        (char*)AsanMmapSomewhereOrDie(size_to_allocate, __FUNCTION__);
148    allocated_end_ = allocated_current_ + size_to_allocate;
149    PoisonShadow((uintptr_t)allocated_current_, size_to_allocate,
150                 kAsanInternalHeapMagic);
151  }
152  CHECK(allocated_end_ - allocated_current_ >= size);
153  void *res = allocated_current_;
154  allocated_current_ += size;
155  return res;
156}
157
158// ---------------------- DescribeAddress -------------------- {{{1
159static bool DescribeStackAddress(uintptr_t addr, uintptr_t access_size) {
160  AsanThread *t = asanThreadRegistry().FindThreadByStackAddress(addr);
161  if (!t) return false;
162  const intptr_t kBufSize = 4095;
163  char buf[kBufSize];
164  uintptr_t offset = 0;
165  const char *frame_descr = t->GetFrameNameByAddr(addr, &offset);
166  // This string is created by the compiler and has the following form:
167  // "FunctioName n alloc_1 alloc_2 ... alloc_n"
168  // where alloc_i looks like "offset size len ObjectName ".
169  CHECK(frame_descr);
170  // Report the function name and the offset.
171  const char *name_end = internal_strchr(frame_descr, ' ');
172  CHECK(name_end);
173  buf[0] = 0;
174  internal_strncat(buf, frame_descr,
175                   Min(kBufSize,
176                       static_cast<intptr_t>(name_end - frame_descr)));
177  Printf("Address %p is located at offset %zu "
178         "in frame <%s> of T%d's stack:\n",
179         addr, offset, buf, t->tid());
180  // Report the number of stack objects.
181  char *p;
182  size_t n_objects = internal_simple_strtoll(name_end, &p, 10);
183  CHECK(n_objects > 0);
184  Printf("  This frame has %zu object(s):\n", n_objects);
185  // Report all objects in this frame.
186  for (size_t i = 0; i < n_objects; i++) {
187    size_t beg, size;
188    intptr_t len;
189    beg  = internal_simple_strtoll(p, &p, 10);
190    size = internal_simple_strtoll(p, &p, 10);
191    len  = internal_simple_strtoll(p, &p, 10);
192    if (beg <= 0 || size <= 0 || len < 0 || *p != ' ') {
193      Printf("AddressSanitizer can't parse the stack frame descriptor: |%s|\n",
194             frame_descr);
195      break;
196    }
197    p++;
198    buf[0] = 0;
199    internal_strncat(buf, p, Min(kBufSize, len));
200    p += len;
201    Printf("    [%zu, %zu) '%s'\n", beg, beg + size, buf);
202  }
203  Printf("HINT: this may be a false positive if your program uses "
204         "some custom stack unwind mechanism\n"
205         "      (longjmp and C++ exceptions *are* supported)\n");
206  t->summary()->Announce();
207  return true;
208}
209
210static NOINLINE void DescribeAddress(uintptr_t addr, uintptr_t access_size) {
211  // Check if this is a global.
212  if (DescribeAddrIfGlobal(addr))
213    return;
214
215  if (DescribeStackAddress(addr, access_size))
216    return;
217
218  // finally, check if this is a heap.
219  DescribeHeapAddress(addr, access_size);
220}
221
222// -------------------------- Run-time entry ------------------- {{{1
223// exported functions
224#define ASAN_REPORT_ERROR(type, is_write, size)                     \
225NOINLINE ASAN_INTERFACE_ATTRIBUTE                                   \
226extern "C" void __asan_report_ ## type ## size(uintptr_t addr);     \
227extern "C" void __asan_report_ ## type ## size(uintptr_t addr) {    \
228  GET_CALLER_PC_BP_SP;                                              \
229  __asan_report_error(pc, bp, sp, addr, is_write, size);            \
230}
231
232ASAN_REPORT_ERROR(load, false, 1)
233ASAN_REPORT_ERROR(load, false, 2)
234ASAN_REPORT_ERROR(load, false, 4)
235ASAN_REPORT_ERROR(load, false, 8)
236ASAN_REPORT_ERROR(load, false, 16)
237ASAN_REPORT_ERROR(store, true, 1)
238ASAN_REPORT_ERROR(store, true, 2)
239ASAN_REPORT_ERROR(store, true, 4)
240ASAN_REPORT_ERROR(store, true, 8)
241ASAN_REPORT_ERROR(store, true, 16)
242
243// Force the linker to keep the symbols for various ASan interface functions.
244// We want to keep those in the executable in order to let the instrumented
245// dynamic libraries access the symbol even if it is not used by the executable
246// itself. This should help if the build system is removing dead code at link
247// time.
248static NOINLINE void force_interface_symbols() {
249  volatile int fake_condition = 0;  // prevent dead condition elimination.
250  if (fake_condition) {
251    __asan_report_load1(0);
252    __asan_report_load2(0);
253    __asan_report_load4(0);
254    __asan_report_load8(0);
255    __asan_report_load16(0);
256    __asan_report_store1(0);
257    __asan_report_store2(0);
258    __asan_report_store4(0);
259    __asan_report_store8(0);
260    __asan_report_store16(0);
261    __asan_register_global(0, 0, NULL);
262    __asan_register_globals(NULL, 0);
263    __asan_unregister_globals(NULL, 0);
264    __asan_set_death_callback(NULL);
265    __asan_set_error_report_callback(NULL);
266    __asan_handle_no_return();
267  }
268}
269
270// -------------------------- Init ------------------- {{{1
271static int64_t IntFlagValue(const char *flags, const char *flag,
272                            int64_t default_val) {
273  if (!flags) return default_val;
274  const char *str = internal_strstr(flags, flag);
275  if (!str) return default_val;
276  return internal_atoll(str + internal_strlen(flag));
277}
278
279static void asan_atexit() {
280  Printf("AddressSanitizer exit stats:\n");
281  __asan_print_accumulated_stats();
282}
283
284void CheckFailed(const char *cond, const char *file, int line) {
285  Report("CHECK failed: %s at %s:%d\n", cond, file, line);
286  PRINT_CURRENT_STACK();
287  ShowStatsAndAbort();
288}
289
290}  // namespace __asan
291
292// ---------------------- Interface ---------------- {{{1
293using namespace __asan;  // NOLINT
294
295int __asan_set_error_exit_code(int exit_code) {
296  int old = FLAG_exitcode;
297  FLAG_exitcode = exit_code;
298  return old;
299}
300
301void NOINLINE __asan_handle_no_return() {
302  int local_stack;
303  AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
304  CHECK(curr_thread);
305  uintptr_t top = curr_thread->stack_top();
306  uintptr_t bottom = ((uintptr_t)&local_stack - kPageSize) & ~(kPageSize-1);
307  PoisonShadow(bottom, top - bottom, 0);
308}
309
310void NOINLINE __asan_set_death_callback(void (*callback)(void)) {
311  death_callback = callback;
312}
313
314void NOINLINE __asan_set_error_report_callback(void (*callback)(const char*)) {
315  error_report_callback = callback;
316  if (callback) {
317    error_message_buffer_size = 1 << 14;
318    error_message_buffer =
319        (char*)AsanMmapSomewhereOrDie(error_message_buffer_size, __FUNCTION__);
320    error_message_buffer_pos = 0;
321  }
322}
323
324void __asan_report_error(uintptr_t pc, uintptr_t bp, uintptr_t sp,
325                         uintptr_t addr, bool is_write, size_t access_size) {
326  // Do not print more than one report, otherwise they will mix up.
327  static int num_calls = 0;
328  if (AtomicInc(&num_calls) > 1) return;
329
330  Printf("=================================================================\n");
331  const char *bug_descr = "unknown-crash";
332  if (AddrIsInMem(addr)) {
333    uint8_t *shadow_addr = (uint8_t*)MemToShadow(addr);
334    // If we are accessing 16 bytes, look at the second shadow byte.
335    if (*shadow_addr == 0 && access_size > SHADOW_GRANULARITY)
336      shadow_addr++;
337    // If we are in the partial right redzone, look at the next shadow byte.
338    if (*shadow_addr > 0 && *shadow_addr < 128)
339      shadow_addr++;
340    switch (*shadow_addr) {
341      case kAsanHeapLeftRedzoneMagic:
342      case kAsanHeapRightRedzoneMagic:
343        bug_descr = "heap-buffer-overflow";
344        break;
345      case kAsanHeapFreeMagic:
346        bug_descr = "heap-use-after-free";
347        break;
348      case kAsanStackLeftRedzoneMagic:
349        bug_descr = "stack-buffer-underflow";
350        break;
351      case kAsanStackMidRedzoneMagic:
352      case kAsanStackRightRedzoneMagic:
353      case kAsanStackPartialRedzoneMagic:
354        bug_descr = "stack-buffer-overflow";
355        break;
356      case kAsanStackAfterReturnMagic:
357        bug_descr = "stack-use-after-return";
358        break;
359      case kAsanUserPoisonedMemoryMagic:
360        bug_descr = "use-after-poison";
361        break;
362      case kAsanGlobalRedzoneMagic:
363        bug_descr = "global-buffer-overflow";
364        break;
365    }
366  }
367
368  AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
369  int curr_tid = asanThreadRegistry().GetCurrentTidOrMinusOne();
370
371  if (curr_thread) {
372    // We started reporting an error message. Stop using the fake stack
373    // in case we will call an instrumented function from a symbolizer.
374    curr_thread->fake_stack().StopUsingFakeStack();
375  }
376
377  Report("ERROR: AddressSanitizer %s on address "
378         "%p at pc 0x%zx bp 0x%zx sp 0x%zx\n",
379         bug_descr, addr, pc, bp, sp);
380
381  Printf("%s of size %zu at %p thread T%d\n",
382         access_size ? (is_write ? "WRITE" : "READ") : "ACCESS",
383         access_size, addr, curr_tid);
384
385  if (FLAG_debug) {
386    PrintBytes("PC: ", (uintptr_t*)pc);
387  }
388
389  GET_STACK_TRACE_WITH_PC_AND_BP(kStackTraceMax, pc, bp);
390  stack.PrintStack();
391
392  CHECK(AddrIsInMem(addr));
393
394  DescribeAddress(addr, access_size);
395
396  uintptr_t shadow_addr = MemToShadow(addr);
397  Report("ABORTING\n");
398  __asan_print_accumulated_stats();
399  Printf("Shadow byte and word:\n");
400  Printf("  %p: %x\n", shadow_addr, *(unsigned char*)shadow_addr);
401  uintptr_t aligned_shadow = shadow_addr & ~(kWordSize - 1);
402  PrintBytes("  ", (uintptr_t*)(aligned_shadow));
403  Printf("More shadow bytes:\n");
404  PrintBytes("  ", (uintptr_t*)(aligned_shadow-4*kWordSize));
405  PrintBytes("  ", (uintptr_t*)(aligned_shadow-3*kWordSize));
406  PrintBytes("  ", (uintptr_t*)(aligned_shadow-2*kWordSize));
407  PrintBytes("  ", (uintptr_t*)(aligned_shadow-1*kWordSize));
408  PrintBytes("=>", (uintptr_t*)(aligned_shadow+0*kWordSize));
409  PrintBytes("  ", (uintptr_t*)(aligned_shadow+1*kWordSize));
410  PrintBytes("  ", (uintptr_t*)(aligned_shadow+2*kWordSize));
411  PrintBytes("  ", (uintptr_t*)(aligned_shadow+3*kWordSize));
412  PrintBytes("  ", (uintptr_t*)(aligned_shadow+4*kWordSize));
413  if (error_report_callback) {
414    error_report_callback(error_message_buffer);
415  }
416  AsanDie();
417}
418
419void __asan_init() {
420  if (asan_inited) return;
421  asan_init_is_running = true;
422
423  // Make sure we are not statically linked.
424  AsanDoesNotSupportStaticLinkage();
425
426  // flags
427  const char *options = AsanGetEnv("ASAN_OPTIONS");
428  FLAG_malloc_context_size =
429      IntFlagValue(options, "malloc_context_size=", kMallocContextSize);
430  CHECK(FLAG_malloc_context_size <= kMallocContextSize);
431
432  FLAG_max_malloc_fill_size =
433      IntFlagValue(options, "max_malloc_fill_size=", 0);
434
435  FLAG_v = IntFlagValue(options, "verbosity=", 0);
436
437  FLAG_redzone = IntFlagValue(options, "redzone=",
438      (ASAN_LOW_MEMORY) ? 64 : 128);
439  CHECK(FLAG_redzone >= 32);
440  CHECK((FLAG_redzone & (FLAG_redzone - 1)) == 0);
441
442  FLAG_atexit = IntFlagValue(options, "atexit=", 0);
443  FLAG_poison_shadow = IntFlagValue(options, "poison_shadow=", 1);
444  FLAG_report_globals = IntFlagValue(options, "report_globals=", 1);
445  FLAG_handle_segv = IntFlagValue(options, "handle_segv=", ASAN_NEEDS_SEGV);
446  FLAG_use_sigaltstack = IntFlagValue(options, "use_sigaltstack=", 0);
447  FLAG_symbolize = IntFlagValue(options, "symbolize=", 1);
448  FLAG_demangle = IntFlagValue(options, "demangle=", 1);
449  FLAG_debug = IntFlagValue(options, "debug=", 0);
450  FLAG_replace_cfallocator = IntFlagValue(options, "replace_cfallocator=", 1);
451  FLAG_replace_str = IntFlagValue(options, "replace_str=", 1);
452  FLAG_replace_intrin = IntFlagValue(options, "replace_intrin=", 1);
453  FLAG_use_fake_stack = IntFlagValue(options, "use_fake_stack=", 1);
454  FLAG_exitcode = IntFlagValue(options, "exitcode=",
455                               ASAN_DEFAULT_FAILURE_EXITCODE);
456  FLAG_allow_user_poisoning = IntFlagValue(options,
457                                           "allow_user_poisoning=", 1);
458  FLAG_sleep_before_dying = IntFlagValue(options, "sleep_before_dying=", 0);
459
460  FLAG_quarantine_size = IntFlagValue(options, "quarantine_size=",
461      (ASAN_LOW_MEMORY) ? 1UL << 24 : 1UL << 28);
462
463  if (FLAG_v) {
464    Report("Parsed ASAN_OPTIONS: %s\n", options);
465  }
466
467  if (FLAG_atexit) {
468    Atexit(asan_atexit);
469  }
470
471  // interceptors
472  InitializeAsanInterceptors();
473
474  ReplaceSystemMalloc();
475
476  if (FLAG_v) {
477    Printf("|| `[%p, %p]` || HighMem    ||\n", kHighMemBeg, kHighMemEnd);
478    Printf("|| `[%p, %p]` || HighShadow ||\n",
479           kHighShadowBeg, kHighShadowEnd);
480    Printf("|| `[%p, %p]` || ShadowGap  ||\n",
481           kShadowGapBeg, kShadowGapEnd);
482    Printf("|| `[%p, %p]` || LowShadow  ||\n",
483           kLowShadowBeg, kLowShadowEnd);
484    Printf("|| `[%p, %p]` || LowMem     ||\n", kLowMemBeg, kLowMemEnd);
485    Printf("MemToShadow(shadow): %p %p %p %p\n",
486           MEM_TO_SHADOW(kLowShadowBeg),
487           MEM_TO_SHADOW(kLowShadowEnd),
488           MEM_TO_SHADOW(kHighShadowBeg),
489           MEM_TO_SHADOW(kHighShadowEnd));
490    Printf("red_zone=%zu\n", (size_t)FLAG_redzone);
491    Printf("malloc_context_size=%zu\n", (size_t)FLAG_malloc_context_size);
492
493    Printf("SHADOW_SCALE: %zx\n", (size_t)SHADOW_SCALE);
494    Printf("SHADOW_GRANULARITY: %zx\n", (size_t)SHADOW_GRANULARITY);
495    Printf("SHADOW_OFFSET: %zx\n", (size_t)SHADOW_OFFSET);
496    CHECK(SHADOW_SCALE >= 3 && SHADOW_SCALE <= 7);
497  }
498
499  if (__WORDSIZE == 64) {
500    // Disable core dumper -- it makes little sense to dump 16T+ core.
501    AsanDisableCoreDumper();
502  }
503
504  if (AsanShadowRangeIsAvailable()) {
505    if (kLowShadowBeg != kLowShadowEnd) {
506      // mmap the low shadow plus at least one page.
507      ReserveShadowMemoryRange(kLowShadowBeg - kMmapGranularity, kLowShadowEnd);
508    }
509    // mmap the high shadow.
510    ReserveShadowMemoryRange(kHighShadowBeg, kHighShadowEnd);
511    // protect the gap
512    void *prot = AsanMprotect(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
513    CHECK(prot == (void*)kShadowGapBeg);
514  } else {
515    Report("Shadow memory range interleaves with an existing memory mapping. "
516           "ASan cannot proceed correctly. ABORTING.\n");
517    AsanDumpProcessMap();
518    AsanDie();
519  }
520
521  InstallSignalHandlers();
522
523  // On Linux AsanThread::ThreadStart() calls malloc() that's why asan_inited
524  // should be set to 1 prior to initializing the threads.
525  asan_inited = 1;
526  asan_init_is_running = false;
527
528  asanThreadRegistry().Init();
529  asanThreadRegistry().GetMain()->ThreadStart();
530  force_interface_symbols();  // no-op.
531
532  if (FLAG_v) {
533    Report("AddressSanitizer Init done\n");
534  }
535}
536
537#if defined(ASAN_USE_PREINIT_ARRAY)
538  // On Linux, we force __asan_init to be called before anyone else
539  // by placing it into .preinit_array section.
540  // FIXME: do we have anything like this on Mac?
541  __attribute__((section(".preinit_array")))
542    typeof(__asan_init) *__asan_preinit =__asan_init;
543#elif defined(_WIN32) && defined(_DLL)
544  // On Windows, when using dynamic CRT (/MD), we can put a pointer
545  // to __asan_init into the global list of C initializers.
546  // See crt0dat.c in the CRT sources for the details.
547  #pragma section(".CRT$XIB", long, read)  // NOLINT
548  __declspec(allocate(".CRT$XIB")) void (*__asan_preinit)() = __asan_init;
549#endif
550