asan_rtl.cc revision 9cfa194cc62026fc7c6e82f7303eee8ad4d10cf4 
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;
50
51// -------------------------- Globals --------------------- {{{1
52int asan_inited;
53bool asan_init_is_running;
54
55// -------------------------- Misc ---------------- {{{1
56void ShowStatsAndAbort() {
57  __asan_print_accumulated_stats();
58  AsanDie();
59}
60
61static void PrintBytes(const char *before, uintptr_t *a) {
62  uint8_t *bytes = (uint8_t*)a;
63  size_t byte_num = (__WORDSIZE) / 8;
64  Printf("%s%p:", before, (uintptr_t)a);
65  for (size_t i = 0; i < byte_num; i++) {
66    Printf(" %lx%lx", bytes[i] >> 4, bytes[i] & 15);
67  }
68  Printf("\n");
69}
70
71size_t ReadFileToBuffer(const char *file_name, char **buff,
72                         size_t *buff_size, size_t max_len) {
73  const size_t kMinFileLen = kPageSize;
74  size_t read_len = 0;
75  *buff = 0;
76  *buff_size = 0;
77  // The files we usually open are not seekable, so try different buffer sizes.
78  for (size_t size = kMinFileLen; size <= max_len; size *= 2) {
79    int fd = AsanOpenReadonly(file_name);
80    if (fd < 0) return -1;
81    AsanUnmapOrDie(*buff, *buff_size);
82    *buff = (char*)AsanMmapSomewhereOrDie(size, __FUNCTION__);
83    *buff_size = size;
84    // Read up to one page at a time.
85    read_len = 0;
86    bool reached_eof = false;
87    while (read_len + kPageSize <= size) {
88      size_t just_read = AsanRead(fd, *buff + read_len, kPageSize);
89      if (just_read == 0) {
90        reached_eof = true;
91        break;
92      }
93      read_len += just_read;
94    }
95    AsanClose(fd);
96    if (reached_eof)  // We've read the whole file.
97      break;
98  }
99  return read_len;
100}
101
102// ---------------------- mmap -------------------- {{{1
103void OutOfMemoryMessageAndDie(const char *mem_type, size_t size) {
104  Report("ERROR: AddressSanitizer failed to allocate "
105         "0x%lx (%ld) bytes of %s\n",
106         size, size, mem_type);
107  PRINT_CURRENT_STACK();
108  ShowStatsAndAbort();
109}
110
111// Reserve memory range [beg, end].
112static void ReserveShadowMemoryRange(uintptr_t beg, uintptr_t end) {
113  CHECK((beg % kPageSize) == 0);
114  CHECK(((end + 1) % kPageSize) == 0);
115  size_t size = end - beg + 1;
116  void *res = AsanMmapFixedNoReserve(beg, size);
117  CHECK(res == (void*)beg && "ReserveShadowMemoryRange failed");
118}
119
120// ---------------------- LowLevelAllocator ------------- {{{1
121void *LowLevelAllocator::Allocate(size_t size) {
122  CHECK((size & (size - 1)) == 0 && "size must be a power of two");
123  if (allocated_end_ - allocated_current_ < size) {
124    size_t size_to_allocate = Max(size, kPageSize);
125    allocated_current_ =
126        (char*)AsanMmapSomewhereOrDie(size_to_allocate, __FUNCTION__);
127    allocated_end_ = allocated_current_ + size_to_allocate;
128    PoisonShadow((uintptr_t)allocated_current_, size_to_allocate,
129                 kAsanInternalHeapMagic);
130  }
131  CHECK(allocated_end_ - allocated_current_ >= size);
132  void *res = allocated_current_;
133  allocated_current_ += size;
134  return res;
135}
136
137// ---------------------- DescribeAddress -------------------- {{{1
138static bool DescribeStackAddress(uintptr_t addr, uintptr_t access_size) {
139  AsanThread *t = asanThreadRegistry().FindThreadByStackAddress(addr);
140  if (!t) return false;
141  const intptr_t kBufSize = 4095;
142  char buf[kBufSize];
143  uintptr_t offset = 0;
144  const char *frame_descr = t->GetFrameNameByAddr(addr, &offset);
145  // This string is created by the compiler and has the following form:
146  // "FunctioName n alloc_1 alloc_2 ... alloc_n"
147  // where alloc_i looks like "offset size len ObjectName ".
148  CHECK(frame_descr);
149  // Report the function name and the offset.
150  const char *name_end = real_strchr(frame_descr, ' ');
151  CHECK(name_end);
152  buf[0] = 0;
153  internal_strncat(buf, frame_descr,
154                   Min(kBufSize,
155                       static_cast<intptr_t>(name_end - frame_descr)));
156  Printf("Address %p is located at offset %ld "
157         "in frame <%s> of T%d's stack:\n",
158         addr, offset, buf, t->tid());
159  // Report the number of stack objects.
160  char *p;
161  size_t n_objects = strtol(name_end, &p, 10);
162  CHECK(n_objects > 0);
163  Printf("  This frame has %ld object(s):\n", n_objects);
164  // Report all objects in this frame.
165  for (size_t i = 0; i < n_objects; i++) {
166    size_t beg, size;
167    intptr_t len;
168    beg  = strtol(p, &p, 10);
169    size = strtol(p, &p, 10);
170    len  = strtol(p, &p, 10);
171    if (beg <= 0 || size <= 0 || len < 0 || *p != ' ') {
172      Printf("AddressSanitizer can't parse the stack frame descriptor: |%s|\n",
173             frame_descr);
174      break;
175    }
176    p++;
177    buf[0] = 0;
178    internal_strncat(buf, p, Min(kBufSize, len));
179    p += len;
180    Printf("    [%ld, %ld) '%s'\n", beg, beg + size, buf);
181  }
182  Printf("HINT: this may be a false positive if your program uses "
183         "some custom stack unwind mechanism\n"
184         "      (longjmp and C++ exceptions *are* supported)\n");
185  t->summary()->Announce();
186  return true;
187}
188
189__attribute__((noinline))
190static void DescribeAddress(uintptr_t addr, uintptr_t access_size) {
191  // Check if this is a global.
192  if (DescribeAddrIfGlobal(addr))
193    return;
194
195  if (DescribeStackAddress(addr, access_size))
196    return;
197
198  // finally, check if this is a heap.
199  DescribeHeapAddress(addr, access_size);
200}
201
202// -------------------------- Run-time entry ------------------- {{{1
203// exported functions
204#define ASAN_REPORT_ERROR(type, is_write, size)                     \
205extern "C" void __asan_report_ ## type ## size(uintptr_t addr)      \
206  __attribute__((visibility("default"))) __attribute__((noinline)); \
207extern "C" void __asan_report_ ## type ## size(uintptr_t addr) {    \
208  GET_BP_PC_SP;                                                     \
209  __asan_report_error(pc, bp, sp, addr, is_write, size);            \
210}
211
212ASAN_REPORT_ERROR(load, false, 1)
213ASAN_REPORT_ERROR(load, false, 2)
214ASAN_REPORT_ERROR(load, false, 4)
215ASAN_REPORT_ERROR(load, false, 8)
216ASAN_REPORT_ERROR(load, false, 16)
217ASAN_REPORT_ERROR(store, true, 1)
218ASAN_REPORT_ERROR(store, true, 2)
219ASAN_REPORT_ERROR(store, true, 4)
220ASAN_REPORT_ERROR(store, true, 8)
221ASAN_REPORT_ERROR(store, true, 16)
222
223// Force the linker to keep the symbols for various ASan interface functions.
224// We want to keep those in the executable in order to let the instrumented
225// dynamic libraries access the symbol even if it is not used by the executable
226// itself. This should help if the build system is removing dead code at link
227// time.
228static void force_interface_symbols() {
229  volatile int fake_condition = 0;  // prevent dead condition elimination.
230  if (fake_condition) {
231    __asan_report_load1(NULL);
232    __asan_report_load2(NULL);
233    __asan_report_load4(NULL);
234    __asan_report_load8(NULL);
235    __asan_report_load16(NULL);
236    __asan_report_store1(NULL);
237    __asan_report_store2(NULL);
238    __asan_report_store4(NULL);
239    __asan_report_store8(NULL);
240    __asan_report_store16(NULL);
241    __asan_register_global(0, 0, NULL);
242    __asan_register_globals(NULL, 0);
243    __asan_unregister_globals(NULL, 0);
244  }
245}
246
247// -------------------------- Init ------------------- {{{1
248static int64_t IntFlagValue(const char *flags, const char *flag,
249                            int64_t default_val) {
250  if (!flags) return default_val;
251  const char *str = internal_strstr(flags, flag);
252  if (!str) return default_val;
253  return atoll(str + internal_strlen(flag));
254}
255
256static void asan_atexit() {
257  Printf("AddressSanitizer exit stats:\n");
258  __asan_print_accumulated_stats();
259}
260
261void CheckFailed(const char *cond, const char *file, int line) {
262  Report("CHECK failed: %s at %s:%d\n", cond, file, line);
263  PRINT_CURRENT_STACK();
264  ShowStatsAndAbort();
265}
266
267}  // namespace __asan
268
269// ---------------------- Interface ---------------- {{{1
270using namespace __asan;  // NOLINT
271
272int __asan_set_error_exit_code(int exit_code) {
273  int old = FLAG_exitcode;
274  FLAG_exitcode = exit_code;
275  return old;
276}
277
278void __asan_report_error(uintptr_t pc, uintptr_t bp, uintptr_t sp,
279                         uintptr_t addr, bool is_write, size_t access_size) {
280  // Do not print more than one report, otherwise they will mix up.
281  static int num_calls = 0;
282  if (AtomicInc(&num_calls) > 1) return;
283
284  Printf("=================================================================\n");
285  const char *bug_descr = "unknown-crash";
286  if (AddrIsInMem(addr)) {
287    uint8_t *shadow_addr = (uint8_t*)MemToShadow(addr);
288    // If we are accessing 16 bytes, look at the second shadow byte.
289    if (*shadow_addr == 0 && access_size > SHADOW_GRANULARITY)
290      shadow_addr++;
291    // If we are in the partial right redzone, look at the next shadow byte.
292    if (*shadow_addr > 0 && *shadow_addr < 128)
293      shadow_addr++;
294    switch (*shadow_addr) {
295      case kAsanHeapLeftRedzoneMagic:
296      case kAsanHeapRightRedzoneMagic:
297        bug_descr = "heap-buffer-overflow";
298        break;
299      case kAsanHeapFreeMagic:
300        bug_descr = "heap-use-after-free";
301        break;
302      case kAsanStackLeftRedzoneMagic:
303        bug_descr = "stack-buffer-underflow";
304        break;
305      case kAsanStackMidRedzoneMagic:
306      case kAsanStackRightRedzoneMagic:
307      case kAsanStackPartialRedzoneMagic:
308        bug_descr = "stack-buffer-overflow";
309        break;
310      case kAsanStackAfterReturnMagic:
311        bug_descr = "stack-use-after-return";
312        break;
313      case kAsanUserPoisonedMemoryMagic:
314        bug_descr = "use-after-poison";
315        break;
316      case kAsanGlobalRedzoneMagic:
317        bug_descr = "global-buffer-overflow";
318        break;
319    }
320  }
321
322  AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
323  int curr_tid = asanThreadRegistry().GetCurrentTidOrMinusOne();
324
325  if (curr_thread) {
326    // We started reporting an error message. Stop using the fake stack
327    // in case we will call an instrumented function from a symbolizer.
328    curr_thread->fake_stack().StopUsingFakeStack();
329  }
330
331  Report("ERROR: AddressSanitizer %s on address "
332         "%p at pc 0x%lx bp 0x%lx sp 0x%lx\n",
333         bug_descr, addr, pc, bp, sp);
334
335  Printf("%s of size %d at %p thread T%d\n",
336         access_size ? (is_write ? "WRITE" : "READ") : "ACCESS",
337         access_size, addr, curr_tid);
338
339  if (FLAG_debug) {
340    PrintBytes("PC: ", (uintptr_t*)pc);
341  }
342
343  GET_STACK_TRACE_WITH_PC_AND_BP(kStackTraceMax, pc, bp);
344  stack.PrintStack();
345
346  CHECK(AddrIsInMem(addr));
347
348  DescribeAddress(addr, access_size);
349
350  uintptr_t shadow_addr = MemToShadow(addr);
351  Report("ABORTING\n");
352  __asan_print_accumulated_stats();
353  Printf("Shadow byte and word:\n");
354  Printf("  %p: %x\n", shadow_addr, *(unsigned char*)shadow_addr);
355  uintptr_t aligned_shadow = shadow_addr & ~(kWordSize - 1);
356  PrintBytes("  ", (uintptr_t*)(aligned_shadow));
357  Printf("More shadow bytes:\n");
358  PrintBytes("  ", (uintptr_t*)(aligned_shadow-4*kWordSize));
359  PrintBytes("  ", (uintptr_t*)(aligned_shadow-3*kWordSize));
360  PrintBytes("  ", (uintptr_t*)(aligned_shadow-2*kWordSize));
361  PrintBytes("  ", (uintptr_t*)(aligned_shadow-1*kWordSize));
362  PrintBytes("=>", (uintptr_t*)(aligned_shadow+0*kWordSize));
363  PrintBytes("  ", (uintptr_t*)(aligned_shadow+1*kWordSize));
364  PrintBytes("  ", (uintptr_t*)(aligned_shadow+2*kWordSize));
365  PrintBytes("  ", (uintptr_t*)(aligned_shadow+3*kWordSize));
366  PrintBytes("  ", (uintptr_t*)(aligned_shadow+4*kWordSize));
367  AsanDie();
368}
369
370void __asan_init() {
371  if (asan_inited) return;
372  asan_init_is_running = true;
373
374  // Make sure we are not statically linked.
375  AsanDoesNotSupportStaticLinkage();
376
377  // flags
378  const char *options = AsanGetEnv("ASAN_OPTIONS");
379  FLAG_malloc_context_size =
380      IntFlagValue(options, "malloc_context_size=", kMallocContextSize);
381  CHECK(FLAG_malloc_context_size <= kMallocContextSize);
382
383  FLAG_max_malloc_fill_size =
384      IntFlagValue(options, "max_malloc_fill_size=", 0);
385
386  FLAG_v = IntFlagValue(options, "verbosity=", 0);
387
388  FLAG_redzone = IntFlagValue(options, "redzone=", 128);
389  CHECK(FLAG_redzone >= 32);
390  CHECK((FLAG_redzone & (FLAG_redzone - 1)) == 0);
391
392  FLAG_atexit = IntFlagValue(options, "atexit=", 0);
393  FLAG_poison_shadow = IntFlagValue(options, "poison_shadow=", 1);
394  FLAG_report_globals = IntFlagValue(options, "report_globals=", 1);
395  FLAG_handle_segv = IntFlagValue(options, "handle_segv=", ASAN_NEEDS_SEGV);
396  FLAG_symbolize = IntFlagValue(options, "symbolize=", 1);
397  FLAG_demangle = IntFlagValue(options, "demangle=", 1);
398  FLAG_debug = IntFlagValue(options, "debug=", 0);
399  FLAG_replace_cfallocator = IntFlagValue(options, "replace_cfallocator=", 1);
400  FLAG_replace_str = IntFlagValue(options, "replace_str=", 1);
401  FLAG_replace_intrin = IntFlagValue(options, "replace_intrin=", 1);
402  FLAG_use_fake_stack = IntFlagValue(options, "use_fake_stack=", 1);
403  FLAG_exitcode = IntFlagValue(options, "exitcode=", EXIT_FAILURE);
404  FLAG_allow_user_poisoning = IntFlagValue(options,
405                                           "allow_user_poisoning=", 1);
406
407  if (FLAG_atexit) {
408    atexit(asan_atexit);
409  }
410
411  FLAG_quarantine_size =
412      IntFlagValue(options, "quarantine_size=", 1UL << 28);
413
414  // interceptors
415  InitializeAsanInterceptors();
416
417  ReplaceSystemMalloc();
418  InstallSignalHandlers();
419
420  if (FLAG_v) {
421    Printf("|| `[%p, %p]` || HighMem    ||\n", kHighMemBeg, kHighMemEnd);
422    Printf("|| `[%p, %p]` || HighShadow ||\n",
423           kHighShadowBeg, kHighShadowEnd);
424    Printf("|| `[%p, %p]` || ShadowGap  ||\n",
425           kShadowGapBeg, kShadowGapEnd);
426    Printf("|| `[%p, %p]` || LowShadow  ||\n",
427           kLowShadowBeg, kLowShadowEnd);
428    Printf("|| `[%p, %p]` || LowMem     ||\n", kLowMemBeg, kLowMemEnd);
429    Printf("MemToShadow(shadow): %p %p %p %p\n",
430           MEM_TO_SHADOW(kLowShadowBeg),
431           MEM_TO_SHADOW(kLowShadowEnd),
432           MEM_TO_SHADOW(kHighShadowBeg),
433           MEM_TO_SHADOW(kHighShadowEnd));
434    Printf("red_zone=%ld\n", FLAG_redzone);
435    Printf("malloc_context_size=%ld\n", (int)FLAG_malloc_context_size);
436
437    Printf("SHADOW_SCALE: %lx\n", SHADOW_SCALE);
438    Printf("SHADOW_GRANULARITY: %lx\n", SHADOW_GRANULARITY);
439    Printf("SHADOW_OFFSET: %lx\n", SHADOW_OFFSET);
440    CHECK(SHADOW_SCALE >= 3 && SHADOW_SCALE <= 7);
441  }
442
443  if (__WORDSIZE == 64) {
444    // Disable core dumper -- it makes little sense to dump 16T+ core.
445    AsanDisableCoreDumper();
446  }
447
448  {
449    if (kLowShadowBeg != kLowShadowEnd) {
450      // mmap the low shadow plus one page.
451      ReserveShadowMemoryRange(kLowShadowBeg - kPageSize, kLowShadowEnd);
452    }
453    // mmap the high shadow.
454    ReserveShadowMemoryRange(kHighShadowBeg, kHighShadowEnd);
455    // protect the gap
456    void *prot = AsanMprotect(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
457    CHECK(prot == (void*)kShadowGapBeg);
458  }
459
460  // On Linux AsanThread::ThreadStart() calls malloc() that's why asan_inited
461  // should be set to 1 prior to initializing the threads.
462  asan_inited = 1;
463  asan_init_is_running = false;
464
465  asanThreadRegistry().Init();
466  asanThreadRegistry().GetMain()->ThreadStart();
467  force_interface_symbols();  // no-op.
468
469  if (FLAG_v) {
470    Report("AddressSanitizer Init done\n");
471  }
472}
473
474#if defined(ASAN_USE_PREINIT_ARRAY)
475// On Linux, we force __asan_init to be called before anyone else
476// by placing it into .preinit_array section.
477// FIXME: do we have anything like this on Mac?
478__attribute__((section(".preinit_array")))
479  typeof(__asan_init) *__asan_preinit =__asan_init;
480#endif
481