asan_rtl.cc revision 788e1d704436065beb514fdde86070f61d0394ed 
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_procmaps.h"
21#include "asan_stack.h"
22#include "asan_stats.h"
23#include "asan_thread.h"
24#include "asan_thread_registry.h"
25
26namespace __asan {
27
28// -------------------------- Flags ------------------------- {{{1
29static const size_t kMallocContextSize = 30;
30static int    FLAG_atexit;
31
32size_t FLAG_redzone;  // power of two, >= 32
33size_t FLAG_quarantine_size;
34int    FLAG_demangle;
35bool   FLAG_symbolize;
36int    FLAG_v;
37int    FLAG_debug;
38bool   FLAG_poison_shadow;
39int    FLAG_report_globals;
40size_t FLAG_malloc_context_size = kMallocContextSize;
41uintptr_t FLAG_large_malloc;
42bool   FLAG_handle_segv;
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 = EXIT_FAILURE;
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);
56
57// -------------------------- Misc ---------------- {{{1
58void ShowStatsAndAbort() {
59  __asan_print_accumulated_stats();
60  AsanDie();
61}
62
63static void PrintBytes(const char *before, uintptr_t *a) {
64  uint8_t *bytes = (uint8_t*)a;
65  size_t byte_num = (__WORDSIZE) / 8;
66  Printf("%s%p:", before, (uintptr_t)a);
67  for (size_t i = 0; i < byte_num; i++) {
68    Printf(" %lx%lx", bytes[i] >> 4, bytes[i] & 15);
69  }
70  Printf("\n");
71}
72
73size_t ReadFileToBuffer(const char *file_name, char **buff,
74                         size_t *buff_size, size_t max_len) {
75  const size_t kMinFileLen = kPageSize;
76  size_t read_len = 0;
77  *buff = 0;
78  *buff_size = 0;
79  // The files we usually open are not seekable, so try different buffer sizes.
80  for (size_t size = kMinFileLen; size <= max_len; size *= 2) {
81    int fd = AsanOpenReadonly(file_name);
82    if (fd < 0) return -1;
83    AsanUnmapOrDie(*buff, *buff_size);
84    *buff = (char*)AsanMmapSomewhereOrDie(size, __FUNCTION__);
85    *buff_size = size;
86    // Read up to one page at a time.
87    read_len = 0;
88    bool reached_eof = false;
89    while (read_len + kPageSize <= size) {
90      size_t just_read = AsanRead(fd, *buff + read_len, kPageSize);
91      if (just_read == 0) {
92        reached_eof = true;
93        break;
94      }
95      read_len += just_read;
96    }
97    AsanClose(fd);
98    if (reached_eof)  // We've read the whole file.
99      break;
100  }
101  return read_len;
102}
103
104void AsanDie() {
105  static int num_calls = 0;
106  if (AtomicInc(&num_calls) > 1) return;  // Don't die twice.
107  if (FLAG_sleep_before_dying) {
108    Report("Sleeping for %d second(s)\n", FLAG_sleep_before_dying);
109    SleepForSeconds(FLAG_sleep_before_dying);
110  }
111  if (death_callback)
112    death_callback();
113  Exit(FLAG_exitcode);
114}
115
116// ---------------------- mmap -------------------- {{{1
117void OutOfMemoryMessageAndDie(const char *mem_type, size_t size) {
118  Report("ERROR: AddressSanitizer failed to allocate "
119         "0x%lx (%ld) bytes of %s\n",
120         size, size, mem_type);
121  PRINT_CURRENT_STACK();
122  ShowStatsAndAbort();
123}
124
125// Reserve memory range [beg, end].
126static void ReserveShadowMemoryRange(uintptr_t beg, uintptr_t end) {
127  CHECK((beg % kPageSize) == 0);
128  CHECK(((end + 1) % kPageSize) == 0);
129  size_t size = end - beg + 1;
130  void *res = AsanMmapFixedNoReserve(beg, size);
131  CHECK(res == (void*)beg && "ReserveShadowMemoryRange failed");
132}
133
134// ---------------------- LowLevelAllocator ------------- {{{1
135void *LowLevelAllocator::Allocate(size_t size) {
136  CHECK((size & (size - 1)) == 0 && "size must be a power of two");
137  if (allocated_end_ - allocated_current_ < size) {
138    size_t size_to_allocate = Max(size, kPageSize);
139    allocated_current_ =
140        (char*)AsanMmapSomewhereOrDie(size_to_allocate, __FUNCTION__);
141    allocated_end_ = allocated_current_ + size_to_allocate;
142    PoisonShadow((uintptr_t)allocated_current_, size_to_allocate,
143                 kAsanInternalHeapMagic);
144  }
145  CHECK(allocated_end_ - allocated_current_ >= size);
146  void *res = allocated_current_;
147  allocated_current_ += size;
148  return res;
149}
150
151// ---------------------- DescribeAddress -------------------- {{{1
152static bool DescribeStackAddress(uintptr_t addr, uintptr_t access_size) {
153  AsanThread *t = asanThreadRegistry().FindThreadByStackAddress(addr);
154  if (!t) return false;
155  const intptr_t kBufSize = 4095;
156  char buf[kBufSize];
157  uintptr_t offset = 0;
158  const char *frame_descr = t->GetFrameNameByAddr(addr, &offset);
159  // This string is created by the compiler and has the following form:
160  // "FunctioName n alloc_1 alloc_2 ... alloc_n"
161  // where alloc_i looks like "offset size len ObjectName ".
162  CHECK(frame_descr);
163  // Report the function name and the offset.
164  const char *name_end = internal_strchr(frame_descr, ' ');
165  CHECK(name_end);
166  buf[0] = 0;
167  internal_strncat(buf, frame_descr,
168                   Min(kBufSize,
169                       static_cast<intptr_t>(name_end - frame_descr)));
170  Printf("Address %p is located at offset %ld "
171         "in frame <%s> of T%d's stack:\n",
172         addr, offset, buf, t->tid());
173  // Report the number of stack objects.
174  char *p;
175  size_t n_objects = strtol(name_end, &p, 10);
176  CHECK(n_objects > 0);
177  Printf("  This frame has %ld object(s):\n", n_objects);
178  // Report all objects in this frame.
179  for (size_t i = 0; i < n_objects; i++) {
180    size_t beg, size;
181    intptr_t len;
182    beg  = strtol(p, &p, 10);
183    size = strtol(p, &p, 10);
184    len  = strtol(p, &p, 10);
185    if (beg <= 0 || size <= 0 || len < 0 || *p != ' ') {
186      Printf("AddressSanitizer can't parse the stack frame descriptor: |%s|\n",
187             frame_descr);
188      break;
189    }
190    p++;
191    buf[0] = 0;
192    internal_strncat(buf, p, Min(kBufSize, len));
193    p += len;
194    Printf("    [%ld, %ld) '%s'\n", beg, beg + size, buf);
195  }
196  Printf("HINT: this may be a false positive if your program uses "
197         "some custom stack unwind mechanism\n"
198         "      (longjmp and C++ exceptions *are* supported)\n");
199  t->summary()->Announce();
200  return true;
201}
202
203static NOINLINE void DescribeAddress(uintptr_t addr, uintptr_t access_size) {
204  // Check if this is a global.
205  if (DescribeAddrIfGlobal(addr))
206    return;
207
208  if (DescribeStackAddress(addr, access_size))
209    return;
210
211  // finally, check if this is a heap.
212  DescribeHeapAddress(addr, access_size);
213}
214
215// -------------------------- Run-time entry ------------------- {{{1
216// exported functions
217#define ASAN_REPORT_ERROR(type, is_write, size)                     \
218NOINLINE ASAN_INTERFACE_ATTRIBUTE                                   \
219extern "C" void __asan_report_ ## type ## size(uintptr_t addr);     \
220extern "C" void __asan_report_ ## type ## size(uintptr_t addr) {    \
221  GET_BP_PC_SP;                                                     \
222  __asan_report_error(pc, bp, sp, addr, is_write, size);            \
223}
224
225ASAN_REPORT_ERROR(load, false, 1)
226ASAN_REPORT_ERROR(load, false, 2)
227ASAN_REPORT_ERROR(load, false, 4)
228ASAN_REPORT_ERROR(load, false, 8)
229ASAN_REPORT_ERROR(load, false, 16)
230ASAN_REPORT_ERROR(store, true, 1)
231ASAN_REPORT_ERROR(store, true, 2)
232ASAN_REPORT_ERROR(store, true, 4)
233ASAN_REPORT_ERROR(store, true, 8)
234ASAN_REPORT_ERROR(store, true, 16)
235
236// Force the linker to keep the symbols for various ASan interface functions.
237// We want to keep those in the executable in order to let the instrumented
238// dynamic libraries access the symbol even if it is not used by the executable
239// itself. This should help if the build system is removing dead code at link
240// time.
241static void force_interface_symbols() {
242  volatile int fake_condition = 0;  // prevent dead condition elimination.
243  if (fake_condition) {
244    __asan_report_load1(NULL);
245    __asan_report_load2(NULL);
246    __asan_report_load4(NULL);
247    __asan_report_load8(NULL);
248    __asan_report_load16(NULL);
249    __asan_report_store1(NULL);
250    __asan_report_store2(NULL);
251    __asan_report_store4(NULL);
252    __asan_report_store8(NULL);
253    __asan_report_store16(NULL);
254    __asan_register_global(0, 0, NULL);
255    __asan_register_globals(NULL, 0);
256    __asan_unregister_globals(NULL, 0);
257  }
258}
259
260// -------------------------- Init ------------------- {{{1
261#if defined(_WIN32)
262// atoll is not defined on Windows.
263int64_t atoll(const char *str) {
264  UNIMPLEMENTED();
265  return -1;
266}
267#endif
268
269static int64_t IntFlagValue(const char *flags, const char *flag,
270                            int64_t default_val) {
271  if (!flags) return default_val;
272  const char *str = internal_strstr(flags, flag);
273  if (!str) return default_val;
274  return atoll(str + internal_strlen(flag));
275}
276
277static void asan_atexit() {
278  Printf("AddressSanitizer exit stats:\n");
279  __asan_print_accumulated_stats();
280}
281
282void CheckFailed(const char *cond, const char *file, int line) {
283  Report("CHECK failed: %s at %s:%d\n", cond, file, line);
284  PRINT_CURRENT_STACK();
285  ShowStatsAndAbort();
286}
287
288}  // namespace __asan
289
290// ---------------------- Interface ---------------- {{{1
291using namespace __asan;  // NOLINT
292
293int __asan_set_error_exit_code(int exit_code) {
294  int old = FLAG_exitcode;
295  FLAG_exitcode = exit_code;
296  return old;
297}
298
299void __asan_handle_no_return() {
300  int local_stack;
301  AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
302  CHECK(curr_thread);
303  uintptr_t top = curr_thread->stack_top();
304  uintptr_t bottom = ((uintptr_t)&local_stack - kPageSize) & ~(kPageSize-1);
305  PoisonShadow(bottom, top - bottom, 0);
306}
307
308void __asan_set_death_callback(void (*callback)(void)) {
309  death_callback = callback;
310}
311
312void __asan_report_error(uintptr_t pc, uintptr_t bp, uintptr_t sp,
313                         uintptr_t addr, bool is_write, size_t access_size) {
314  // Do not print more than one report, otherwise they will mix up.
315  static int num_calls = 0;
316  if (AtomicInc(&num_calls) > 1) return;
317
318  Printf("=================================================================\n");
319  const char *bug_descr = "unknown-crash";
320  if (AddrIsInMem(addr)) {
321    uint8_t *shadow_addr = (uint8_t*)MemToShadow(addr);
322    // If we are accessing 16 bytes, look at the second shadow byte.
323    if (*shadow_addr == 0 && access_size > SHADOW_GRANULARITY)
324      shadow_addr++;
325    // If we are in the partial right redzone, look at the next shadow byte.
326    if (*shadow_addr > 0 && *shadow_addr < 128)
327      shadow_addr++;
328    switch (*shadow_addr) {
329      case kAsanHeapLeftRedzoneMagic:
330      case kAsanHeapRightRedzoneMagic:
331        bug_descr = "heap-buffer-overflow";
332        break;
333      case kAsanHeapFreeMagic:
334        bug_descr = "heap-use-after-free";
335        break;
336      case kAsanStackLeftRedzoneMagic:
337        bug_descr = "stack-buffer-underflow";
338        break;
339      case kAsanStackMidRedzoneMagic:
340      case kAsanStackRightRedzoneMagic:
341      case kAsanStackPartialRedzoneMagic:
342        bug_descr = "stack-buffer-overflow";
343        break;
344      case kAsanStackAfterReturnMagic:
345        bug_descr = "stack-use-after-return";
346        break;
347      case kAsanUserPoisonedMemoryMagic:
348        bug_descr = "use-after-poison";
349        break;
350      case kAsanGlobalRedzoneMagic:
351        bug_descr = "global-buffer-overflow";
352        break;
353    }
354  }
355
356  AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
357  int curr_tid = asanThreadRegistry().GetCurrentTidOrMinusOne();
358
359  if (curr_thread) {
360    // We started reporting an error message. Stop using the fake stack
361    // in case we will call an instrumented function from a symbolizer.
362    curr_thread->fake_stack().StopUsingFakeStack();
363  }
364
365  Report("ERROR: AddressSanitizer %s on address "
366         "%p at pc 0x%lx bp 0x%lx sp 0x%lx\n",
367         bug_descr, addr, pc, bp, sp);
368
369  Printf("%s of size %d at %p thread T%d\n",
370         access_size ? (is_write ? "WRITE" : "READ") : "ACCESS",
371         access_size, addr, curr_tid);
372
373  if (FLAG_debug) {
374    PrintBytes("PC: ", (uintptr_t*)pc);
375  }
376
377  GET_STACK_TRACE_WITH_PC_AND_BP(kStackTraceMax, pc, bp);
378  stack.PrintStack();
379
380  CHECK(AddrIsInMem(addr));
381
382  DescribeAddress(addr, access_size);
383
384  uintptr_t shadow_addr = MemToShadow(addr);
385  Report("ABORTING\n");
386  __asan_print_accumulated_stats();
387  Printf("Shadow byte and word:\n");
388  Printf("  %p: %x\n", shadow_addr, *(unsigned char*)shadow_addr);
389  uintptr_t aligned_shadow = shadow_addr & ~(kWordSize - 1);
390  PrintBytes("  ", (uintptr_t*)(aligned_shadow));
391  Printf("More shadow bytes:\n");
392  PrintBytes("  ", (uintptr_t*)(aligned_shadow-4*kWordSize));
393  PrintBytes("  ", (uintptr_t*)(aligned_shadow-3*kWordSize));
394  PrintBytes("  ", (uintptr_t*)(aligned_shadow-2*kWordSize));
395  PrintBytes("  ", (uintptr_t*)(aligned_shadow-1*kWordSize));
396  PrintBytes("=>", (uintptr_t*)(aligned_shadow+0*kWordSize));
397  PrintBytes("  ", (uintptr_t*)(aligned_shadow+1*kWordSize));
398  PrintBytes("  ", (uintptr_t*)(aligned_shadow+2*kWordSize));
399  PrintBytes("  ", (uintptr_t*)(aligned_shadow+3*kWordSize));
400  PrintBytes("  ", (uintptr_t*)(aligned_shadow+4*kWordSize));
401  AsanDie();
402}
403
404void __asan_init() {
405  if (asan_inited) return;
406  asan_init_is_running = true;
407
408  // Make sure we are not statically linked.
409  AsanDoesNotSupportStaticLinkage();
410
411  // flags
412  const char *options = AsanGetEnv("ASAN_OPTIONS");
413  FLAG_malloc_context_size =
414      IntFlagValue(options, "malloc_context_size=", kMallocContextSize);
415  CHECK(FLAG_malloc_context_size <= kMallocContextSize);
416
417  FLAG_max_malloc_fill_size =
418      IntFlagValue(options, "max_malloc_fill_size=", 0);
419
420  FLAG_v = IntFlagValue(options, "verbosity=", 0);
421
422#if ASAN_LOW_MEMORY == 1
423  FLAG_quarantine_size =
424    IntFlagValue(options, "quarantine_size=", 1UL << 24); // 16M
425  FLAG_redzone = IntFlagValue(options, "redzone=", 64);
426#else
427  FLAG_quarantine_size =
428    IntFlagValue(options, "quarantine_size=", 1UL << 28); // 256M
429  FLAG_redzone = IntFlagValue(options, "redzone=", 128);
430#endif
431  CHECK(FLAG_redzone >= 32);
432  CHECK((FLAG_redzone & (FLAG_redzone - 1)) == 0);
433
434  FLAG_atexit = IntFlagValue(options, "atexit=", 0);
435  FLAG_poison_shadow = IntFlagValue(options, "poison_shadow=", 1);
436  FLAG_report_globals = IntFlagValue(options, "report_globals=", 1);
437  FLAG_handle_segv = IntFlagValue(options, "handle_segv=", ASAN_NEEDS_SEGV);
438  FLAG_symbolize = IntFlagValue(options, "symbolize=", 1);
439  FLAG_demangle = IntFlagValue(options, "demangle=", 1);
440  FLAG_debug = IntFlagValue(options, "debug=", 0);
441  FLAG_replace_cfallocator = IntFlagValue(options, "replace_cfallocator=", 1);
442  FLAG_replace_str = IntFlagValue(options, "replace_str=", 1);
443  FLAG_replace_intrin = IntFlagValue(options, "replace_intrin=", 1);
444  FLAG_use_fake_stack = IntFlagValue(options, "use_fake_stack=", 1);
445  FLAG_exitcode = IntFlagValue(options, "exitcode=", EXIT_FAILURE);
446  FLAG_allow_user_poisoning = IntFlagValue(options,
447                                           "allow_user_poisoning=", 1);
448  FLAG_sleep_before_dying = IntFlagValue(options, "sleep_before_dying=", 0);
449
450  if (FLAG_atexit) {
451    atexit(asan_atexit);
452  }
453
454  // interceptors
455  InitializeAsanInterceptors();
456
457  ReplaceSystemMalloc();
458  InstallSignalHandlers();
459
460  if (FLAG_v) {
461    Printf("|| `[%p, %p]` || HighMem    ||\n", kHighMemBeg, kHighMemEnd);
462    Printf("|| `[%p, %p]` || HighShadow ||\n",
463           kHighShadowBeg, kHighShadowEnd);
464    Printf("|| `[%p, %p]` || ShadowGap  ||\n",
465           kShadowGapBeg, kShadowGapEnd);
466    Printf("|| `[%p, %p]` || LowShadow  ||\n",
467           kLowShadowBeg, kLowShadowEnd);
468    Printf("|| `[%p, %p]` || LowMem     ||\n", kLowMemBeg, kLowMemEnd);
469    Printf("MemToShadow(shadow): %p %p %p %p\n",
470           MEM_TO_SHADOW(kLowShadowBeg),
471           MEM_TO_SHADOW(kLowShadowEnd),
472           MEM_TO_SHADOW(kHighShadowBeg),
473           MEM_TO_SHADOW(kHighShadowEnd));
474    Printf("red_zone=%ld\n", FLAG_redzone);
475    Printf("malloc_context_size=%ld\n", (int)FLAG_malloc_context_size);
476
477    Printf("SHADOW_SCALE: %lx\n", SHADOW_SCALE);
478    Printf("SHADOW_GRANULARITY: %lx\n", SHADOW_GRANULARITY);
479    Printf("SHADOW_OFFSET: %lx\n", SHADOW_OFFSET);
480    CHECK(SHADOW_SCALE >= 3 && SHADOW_SCALE <= 7);
481  }
482
483  if (__WORDSIZE == 64) {
484    // Disable core dumper -- it makes little sense to dump 16T+ core.
485    AsanDisableCoreDumper();
486  }
487
488  if (AsanShadowRangeIsAvailable()) {
489    if (kLowShadowBeg != kLowShadowEnd) {
490      // mmap the low shadow plus at least one page.
491      ReserveShadowMemoryRange(kLowShadowBeg - kMmapGranularity, kLowShadowEnd);
492    }
493    // mmap the high shadow.
494    ReserveShadowMemoryRange(kHighShadowBeg, kHighShadowEnd);
495    // protect the gap
496    void *prot = AsanMprotect(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
497    CHECK(prot == (void*)kShadowGapBeg);
498  } else {
499    Report("Shadow memory range interleaves with an existing memory mapping. "
500           "ASan cannot proceed correctly. ABORTING.\n");
501    AsanDie();
502  }
503
504  // On Linux AsanThread::ThreadStart() calls malloc() that's why asan_inited
505  // should be set to 1 prior to initializing the threads.
506  asan_inited = 1;
507  asan_init_is_running = false;
508
509  asanThreadRegistry().Init();
510  asanThreadRegistry().GetMain()->ThreadStart();
511  force_interface_symbols();  // no-op.
512
513  if (FLAG_v) {
514    Report("AddressSanitizer Init done\n");
515  }
516}
517
518#if defined(ASAN_USE_PREINIT_ARRAY)
519// On Linux, we force __asan_init to be called before anyone else
520// by placing it into .preinit_array section.
521// FIXME: do we have anything like this on Mac?
522__attribute__((section(".preinit_array")))
523  typeof(__asan_init) *__asan_preinit =__asan_init;
524#endif
525