asan_rtl.cc revision f54b1f9b73a6855d77ee270c282bd61407fa73a0 
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;
55
56// -------------------------- Misc ---------------- {{{1
57void ShowStatsAndAbort() {
58  __asan_print_accumulated_stats();
59  AsanDie();
60}
61
62static void PrintBytes(const char *before, uintptr_t *a) {
63  uint8_t *bytes = (uint8_t*)a;
64  size_t byte_num = (__WORDSIZE) / 8;
65  Printf("%s%p:", before, (uintptr_t)a);
66  for (size_t i = 0; i < byte_num; i++) {
67    Printf(" %lx%lx", bytes[i] >> 4, bytes[i] & 15);
68  }
69  Printf("\n");
70}
71
72size_t ReadFileToBuffer(const char *file_name, char **buff,
73                         size_t *buff_size, size_t max_len) {
74  const size_t kMinFileLen = kPageSize;
75  size_t read_len = 0;
76  *buff = 0;
77  *buff_size = 0;
78  // The files we usually open are not seekable, so try different buffer sizes.
79  for (size_t size = kMinFileLen; size <= max_len; size *= 2) {
80    int fd = AsanOpenReadonly(file_name);
81    if (fd < 0) return -1;
82    AsanUnmapOrDie(*buff, *buff_size);
83    *buff = (char*)AsanMmapSomewhereOrDie(size, __FUNCTION__);
84    *buff_size = size;
85    // Read up to one page at a time.
86    read_len = 0;
87    bool reached_eof = false;
88    while (read_len + kPageSize <= size) {
89      size_t just_read = AsanRead(fd, *buff + read_len, kPageSize);
90      if (just_read == 0) {
91        reached_eof = true;
92        break;
93      }
94      read_len += just_read;
95    }
96    AsanClose(fd);
97    if (reached_eof)  // We've read the whole file.
98      break;
99  }
100  return read_len;
101}
102
103// ---------------------- mmap -------------------- {{{1
104void OutOfMemoryMessageAndDie(const char *mem_type, size_t size) {
105  Report("ERROR: AddressSanitizer failed to allocate "
106         "0x%lx (%ld) bytes of %s\n",
107         size, size, mem_type);
108  PRINT_CURRENT_STACK();
109  ShowStatsAndAbort();
110}
111
112// Reserve memory range [beg, end].
113static void ReserveShadowMemoryRange(uintptr_t beg, uintptr_t end) {
114  CHECK((beg % kPageSize) == 0);
115  CHECK(((end + 1) % kPageSize) == 0);
116  size_t size = end - beg + 1;
117  void *res = AsanMmapFixedNoReserve(beg, size);
118  CHECK(res == (void*)beg && "ReserveShadowMemoryRange failed");
119}
120
121// ---------------------- LowLevelAllocator ------------- {{{1
122void *LowLevelAllocator::Allocate(size_t size) {
123  CHECK((size & (size - 1)) == 0 && "size must be a power of two");
124  if (allocated_end_ - allocated_current_ < size) {
125    size_t size_to_allocate = Max(size, kPageSize);
126    allocated_current_ =
127        (char*)AsanMmapSomewhereOrDie(size_to_allocate, __FUNCTION__);
128    allocated_end_ = allocated_current_ + size_to_allocate;
129    PoisonShadow((uintptr_t)allocated_current_, size_to_allocate,
130                 kAsanInternalHeapMagic);
131  }
132  CHECK(allocated_end_ - allocated_current_ >= size);
133  void *res = allocated_current_;
134  allocated_current_ += size;
135  return res;
136}
137
138// ---------------------- DescribeAddress -------------------- {{{1
139static bool DescribeStackAddress(uintptr_t addr, uintptr_t access_size) {
140  AsanThread *t = asanThreadRegistry().FindThreadByStackAddress(addr);
141  if (!t) return false;
142  const intptr_t kBufSize = 4095;
143  char buf[kBufSize];
144  uintptr_t offset = 0;
145  const char *frame_descr = t->GetFrameNameByAddr(addr, &offset);
146  // This string is created by the compiler and has the following form:
147  // "FunctioName n alloc_1 alloc_2 ... alloc_n"
148  // where alloc_i looks like "offset size len ObjectName ".
149  CHECK(frame_descr);
150  // Report the function name and the offset.
151  const char *name_end = REAL(strchr)(frame_descr, ' ');
152  CHECK(name_end);
153  buf[0] = 0;
154  internal_strncat(buf, frame_descr,
155                   Min(kBufSize,
156                       static_cast<intptr_t>(name_end - frame_descr)));
157  Printf("Address %p is located at offset %ld "
158         "in frame <%s> of T%d's stack:\n",
159         addr, offset, buf, t->tid());
160  // Report the number of stack objects.
161  char *p;
162  size_t n_objects = strtol(name_end, &p, 10);
163  CHECK(n_objects > 0);
164  Printf("  This frame has %ld object(s):\n", n_objects);
165  // Report all objects in this frame.
166  for (size_t i = 0; i < n_objects; i++) {
167    size_t beg, size;
168    intptr_t len;
169    beg  = strtol(p, &p, 10);
170    size = strtol(p, &p, 10);
171    len  = strtol(p, &p, 10);
172    if (beg <= 0 || size <= 0 || len < 0 || *p != ' ') {
173      Printf("AddressSanitizer can't parse the stack frame descriptor: |%s|\n",
174             frame_descr);
175      break;
176    }
177    p++;
178    buf[0] = 0;
179    internal_strncat(buf, p, Min(kBufSize, len));
180    p += len;
181    Printf("    [%ld, %ld) '%s'\n", beg, beg + size, buf);
182  }
183  Printf("HINT: this may be a false positive if your program uses "
184         "some custom stack unwind mechanism\n"
185         "      (longjmp and C++ exceptions *are* supported)\n");
186  t->summary()->Announce();
187  return true;
188}
189
190static NOINLINE 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)                     \
205NOINLINE ASAN_INTERFACE_ATTRIBUTE                                   \
206extern "C" void __asan_report_ ## type ## size(uintptr_t addr);     \
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
248#if defined(_WIN32)
249// atoll is not defined on Windows.
250int64_t atoll(const char *str) {
251  UNIMPLEMENTED();
252  return -1;
253}
254#endif
255
256static int64_t IntFlagValue(const char *flags, const char *flag,
257                            int64_t default_val) {
258  if (!flags) return default_val;
259  const char *str = internal_strstr(flags, flag);
260  if (!str) return default_val;
261  return atoll(str + internal_strlen(flag));
262}
263
264static void asan_atexit() {
265  Printf("AddressSanitizer exit stats:\n");
266  __asan_print_accumulated_stats();
267}
268
269void CheckFailed(const char *cond, const char *file, int line) {
270  Report("CHECK failed: %s at %s:%d\n", cond, file, line);
271  PRINT_CURRENT_STACK();
272  ShowStatsAndAbort();
273}
274
275}  // namespace __asan
276
277// ---------------------- Interface ---------------- {{{1
278using namespace __asan;  // NOLINT
279
280int __asan_set_error_exit_code(int exit_code) {
281  int old = FLAG_exitcode;
282  FLAG_exitcode = exit_code;
283  return old;
284}
285
286void __asan_handle_no_return() {
287  int local_stack;
288  AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
289  CHECK(curr_thread);
290  uintptr_t top = curr_thread->stack_top();
291  uintptr_t bottom = ((uintptr_t)&local_stack - kPageSize) & ~(kPageSize-1);
292  PoisonShadow(bottom, top - bottom, 0);
293}
294
295void __asan_report_error(uintptr_t pc, uintptr_t bp, uintptr_t sp,
296                         uintptr_t addr, bool is_write, size_t access_size) {
297  // Do not print more than one report, otherwise they will mix up.
298  static int num_calls = 0;
299  if (AtomicInc(&num_calls) > 1) return;
300
301  Printf("=================================================================\n");
302  const char *bug_descr = "unknown-crash";
303  if (AddrIsInMem(addr)) {
304    uint8_t *shadow_addr = (uint8_t*)MemToShadow(addr);
305    // If we are accessing 16 bytes, look at the second shadow byte.
306    if (*shadow_addr == 0 && access_size > SHADOW_GRANULARITY)
307      shadow_addr++;
308    // If we are in the partial right redzone, look at the next shadow byte.
309    if (*shadow_addr > 0 && *shadow_addr < 128)
310      shadow_addr++;
311    switch (*shadow_addr) {
312      case kAsanHeapLeftRedzoneMagic:
313      case kAsanHeapRightRedzoneMagic:
314        bug_descr = "heap-buffer-overflow";
315        break;
316      case kAsanHeapFreeMagic:
317        bug_descr = "heap-use-after-free";
318        break;
319      case kAsanStackLeftRedzoneMagic:
320        bug_descr = "stack-buffer-underflow";
321        break;
322      case kAsanStackMidRedzoneMagic:
323      case kAsanStackRightRedzoneMagic:
324      case kAsanStackPartialRedzoneMagic:
325        bug_descr = "stack-buffer-overflow";
326        break;
327      case kAsanStackAfterReturnMagic:
328        bug_descr = "stack-use-after-return";
329        break;
330      case kAsanUserPoisonedMemoryMagic:
331        bug_descr = "use-after-poison";
332        break;
333      case kAsanGlobalRedzoneMagic:
334        bug_descr = "global-buffer-overflow";
335        break;
336    }
337  }
338
339  AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
340  int curr_tid = asanThreadRegistry().GetCurrentTidOrMinusOne();
341
342  if (curr_thread) {
343    // We started reporting an error message. Stop using the fake stack
344    // in case we will call an instrumented function from a symbolizer.
345    curr_thread->fake_stack().StopUsingFakeStack();
346  }
347
348  Report("ERROR: AddressSanitizer %s on address "
349         "%p at pc 0x%lx bp 0x%lx sp 0x%lx\n",
350         bug_descr, addr, pc, bp, sp);
351
352  Printf("%s of size %d at %p thread T%d\n",
353         access_size ? (is_write ? "WRITE" : "READ") : "ACCESS",
354         access_size, addr, curr_tid);
355
356  if (FLAG_debug) {
357    PrintBytes("PC: ", (uintptr_t*)pc);
358  }
359
360  GET_STACK_TRACE_WITH_PC_AND_BP(kStackTraceMax, pc, bp);
361  stack.PrintStack();
362
363  CHECK(AddrIsInMem(addr));
364
365  DescribeAddress(addr, access_size);
366
367  uintptr_t shadow_addr = MemToShadow(addr);
368  Report("ABORTING\n");
369  __asan_print_accumulated_stats();
370  Printf("Shadow byte and word:\n");
371  Printf("  %p: %x\n", shadow_addr, *(unsigned char*)shadow_addr);
372  uintptr_t aligned_shadow = shadow_addr & ~(kWordSize - 1);
373  PrintBytes("  ", (uintptr_t*)(aligned_shadow));
374  Printf("More shadow bytes:\n");
375  PrintBytes("  ", (uintptr_t*)(aligned_shadow-4*kWordSize));
376  PrintBytes("  ", (uintptr_t*)(aligned_shadow-3*kWordSize));
377  PrintBytes("  ", (uintptr_t*)(aligned_shadow-2*kWordSize));
378  PrintBytes("  ", (uintptr_t*)(aligned_shadow-1*kWordSize));
379  PrintBytes("=>", (uintptr_t*)(aligned_shadow+0*kWordSize));
380  PrintBytes("  ", (uintptr_t*)(aligned_shadow+1*kWordSize));
381  PrintBytes("  ", (uintptr_t*)(aligned_shadow+2*kWordSize));
382  PrintBytes("  ", (uintptr_t*)(aligned_shadow+3*kWordSize));
383  PrintBytes("  ", (uintptr_t*)(aligned_shadow+4*kWordSize));
384  AsanDie();
385}
386
387void __asan_init() {
388  if (asan_inited) return;
389  asan_init_is_running = true;
390
391  // Make sure we are not statically linked.
392  AsanDoesNotSupportStaticLinkage();
393
394  // flags
395  const char *options = AsanGetEnv("ASAN_OPTIONS");
396  FLAG_malloc_context_size =
397      IntFlagValue(options, "malloc_context_size=", kMallocContextSize);
398  CHECK(FLAG_malloc_context_size <= kMallocContextSize);
399
400  FLAG_max_malloc_fill_size =
401      IntFlagValue(options, "max_malloc_fill_size=", 0);
402
403  FLAG_v = IntFlagValue(options, "verbosity=", 0);
404
405  FLAG_redzone = IntFlagValue(options, "redzone=", 128);
406  CHECK(FLAG_redzone >= 32);
407  CHECK((FLAG_redzone & (FLAG_redzone - 1)) == 0);
408
409  FLAG_atexit = IntFlagValue(options, "atexit=", 0);
410  FLAG_poison_shadow = IntFlagValue(options, "poison_shadow=", 1);
411  FLAG_report_globals = IntFlagValue(options, "report_globals=", 1);
412  FLAG_handle_segv = IntFlagValue(options, "handle_segv=", ASAN_NEEDS_SEGV);
413  FLAG_symbolize = IntFlagValue(options, "symbolize=", 1);
414  FLAG_demangle = IntFlagValue(options, "demangle=", 1);
415  FLAG_debug = IntFlagValue(options, "debug=", 0);
416  FLAG_replace_cfallocator = IntFlagValue(options, "replace_cfallocator=", 1);
417  FLAG_replace_str = IntFlagValue(options, "replace_str=", 1);
418  FLAG_replace_intrin = IntFlagValue(options, "replace_intrin=", 1);
419  FLAG_use_fake_stack = IntFlagValue(options, "use_fake_stack=", 1);
420  FLAG_exitcode = IntFlagValue(options, "exitcode=", EXIT_FAILURE);
421  FLAG_allow_user_poisoning = IntFlagValue(options,
422                                           "allow_user_poisoning=", 1);
423  FLAG_sleep_before_dying = IntFlagValue(options, "sleep_before_dying=", 0);
424
425  if (FLAG_atexit) {
426    atexit(asan_atexit);
427  }
428
429  FLAG_quarantine_size =
430      IntFlagValue(options, "quarantine_size=", 1UL << 28);
431
432  // interceptors
433  InitializeAsanInterceptors();
434
435  ReplaceSystemMalloc();
436  InstallSignalHandlers();
437
438  if (FLAG_v) {
439    Printf("|| `[%p, %p]` || HighMem    ||\n", kHighMemBeg, kHighMemEnd);
440    Printf("|| `[%p, %p]` || HighShadow ||\n",
441           kHighShadowBeg, kHighShadowEnd);
442    Printf("|| `[%p, %p]` || ShadowGap  ||\n",
443           kShadowGapBeg, kShadowGapEnd);
444    Printf("|| `[%p, %p]` || LowShadow  ||\n",
445           kLowShadowBeg, kLowShadowEnd);
446    Printf("|| `[%p, %p]` || LowMem     ||\n", kLowMemBeg, kLowMemEnd);
447    Printf("MemToShadow(shadow): %p %p %p %p\n",
448           MEM_TO_SHADOW(kLowShadowBeg),
449           MEM_TO_SHADOW(kLowShadowEnd),
450           MEM_TO_SHADOW(kHighShadowBeg),
451           MEM_TO_SHADOW(kHighShadowEnd));
452    Printf("red_zone=%ld\n", FLAG_redzone);
453    Printf("malloc_context_size=%ld\n", (int)FLAG_malloc_context_size);
454
455    Printf("SHADOW_SCALE: %lx\n", SHADOW_SCALE);
456    Printf("SHADOW_GRANULARITY: %lx\n", SHADOW_GRANULARITY);
457    Printf("SHADOW_OFFSET: %lx\n", SHADOW_OFFSET);
458    CHECK(SHADOW_SCALE >= 3 && SHADOW_SCALE <= 7);
459  }
460
461  if (__WORDSIZE == 64) {
462    // Disable core dumper -- it makes little sense to dump 16T+ core.
463    AsanDisableCoreDumper();
464  }
465
466  {
467    if (kLowShadowBeg != kLowShadowEnd) {
468      // mmap the low shadow plus one page.
469      ReserveShadowMemoryRange(kLowShadowBeg - kPageSize, kLowShadowEnd);
470    }
471    // mmap the high shadow.
472    ReserveShadowMemoryRange(kHighShadowBeg, kHighShadowEnd);
473    // protect the gap
474    void *prot = AsanMprotect(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
475    CHECK(prot == (void*)kShadowGapBeg);
476  }
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 (FLAG_v) {
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#endif
499