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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_internal.h"
17 #include "asan_mapping.h"
18 #include "asan_report.h"
19 #include "asan_stack.h"
20 #include "asan_stats.h"
21 #include "asan_thread.h"
22 #include "asan_thread_registry.h"
23 #include "sanitizer_common/sanitizer_atomic.h"
24 #include "sanitizer_common/sanitizer_flags.h"
25 #include "sanitizer_common/sanitizer_libc.h"
26 #include "sanitizer_common/sanitizer_symbolizer.h"
27 
28 namespace __asan {
29 
30 uptr AsanMappingProfile[kAsanMappingProfileSize];
31 
AsanDie()32 static void AsanDie() {
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     if (kMidMemBeg) {
44       UnmapOrDie((void*)kLowShadowBeg, kMidMemBeg - kLowShadowBeg);
45       UnmapOrDie((void*)kMidMemEnd, kHighShadowEnd - kMidMemEnd);
46     } else {
47       UnmapOrDie((void*)kLowShadowBeg, kHighShadowEnd - kLowShadowBeg);
48     }
49   }
50   if (death_callback)
51     death_callback();
52   if (flags()->abort_on_error)
53     Abort();
54   internal__exit(flags()->exitcode);
55 }
56 
AsanCheckFailed(const char * file,int line,const char * cond,u64 v1,u64 v2)57 static void AsanCheckFailed(const char *file, int line, const char *cond,
58                             u64 v1, u64 v2) {
59   Report("AddressSanitizer CHECK failed: %s:%d \"%s\" (0x%zx, 0x%zx)\n",
60              file, line, cond, (uptr)v1, (uptr)v2);
61   // FIXME: check for infinite recursion without a thread-local counter here.
62   PRINT_CURRENT_STACK();
63   Die();
64 }
65 
66 // -------------------------- Flags ------------------------- {{{1
67 static const int kDeafultMallocContextSize = 30;
68 
69 static Flags asan_flags;
70 
flags()71 Flags *flags() {
72   return &asan_flags;
73 }
74 
MaybeCallAsanDefaultOptions()75 static const char *MaybeCallAsanDefaultOptions() {
76   return (&__asan_default_options) ? __asan_default_options() : "";
77 }
78 
MaybeUseAsanDefaultOptionsCompileDefiniton()79 static const char *MaybeUseAsanDefaultOptionsCompileDefiniton() {
80 #ifdef ASAN_DEFAULT_OPTIONS
81 // Stringize the macro value.
82 # define ASAN_STRINGIZE(x) #x
83 # define ASAN_STRINGIZE_OPTIONS(options) ASAN_STRINGIZE(options)
84   return ASAN_STRINGIZE_OPTIONS(ASAN_DEFAULT_OPTIONS);
85 #else
86   return "";
87 #endif
88 }
89 
ParseFlagsFromString(Flags * f,const char * str)90 static void ParseFlagsFromString(Flags *f, const char *str) {
91   ParseFlag(str, &f->quarantine_size, "quarantine_size");
92   ParseFlag(str, &f->symbolize, "symbolize");
93   ParseFlag(str, &f->verbosity, "verbosity");
94   ParseFlag(str, &f->redzone, "redzone");
95   CHECK(f->redzone >= 16);
96   CHECK(IsPowerOfTwo(f->redzone));
97 
98   ParseFlag(str, &f->debug, "debug");
99   ParseFlag(str, &f->report_globals, "report_globals");
100   ParseFlag(str, &f->check_initialization_order, "initialization_order");
101   ParseFlag(str, &f->malloc_context_size, "malloc_context_size");
102   CHECK((uptr)f->malloc_context_size <= kStackTraceMax);
103 
104   ParseFlag(str, &f->replace_str, "replace_str");
105   ParseFlag(str, &f->replace_intrin, "replace_intrin");
106   ParseFlag(str, &f->mac_ignore_invalid_free, "mac_ignore_invalid_free");
107   ParseFlag(str, &f->use_fake_stack, "use_fake_stack");
108   ParseFlag(str, &f->max_malloc_fill_size, "max_malloc_fill_size");
109   ParseFlag(str, &f->exitcode, "exitcode");
110   ParseFlag(str, &f->allow_user_poisoning, "allow_user_poisoning");
111   ParseFlag(str, &f->sleep_before_dying, "sleep_before_dying");
112   ParseFlag(str, &f->handle_segv, "handle_segv");
113   ParseFlag(str, &f->use_sigaltstack, "use_sigaltstack");
114   ParseFlag(str, &f->check_malloc_usable_size, "check_malloc_usable_size");
115   ParseFlag(str, &f->unmap_shadow_on_exit, "unmap_shadow_on_exit");
116   ParseFlag(str, &f->abort_on_error, "abort_on_error");
117   ParseFlag(str, &f->print_stats, "print_stats");
118   ParseFlag(str, &f->print_legend, "print_legend");
119   ParseFlag(str, &f->atexit, "atexit");
120   ParseFlag(str, &f->disable_core, "disable_core");
121   ParseFlag(str, &f->strip_path_prefix, "strip_path_prefix");
122   ParseFlag(str, &f->allow_reexec, "allow_reexec");
123   ParseFlag(str, &f->print_full_thread_history, "print_full_thread_history");
124   ParseFlag(str, &f->log_path, "log_path");
125   ParseFlag(str, &f->fast_unwind_on_fatal, "fast_unwind_on_fatal");
126   ParseFlag(str, &f->fast_unwind_on_malloc, "fast_unwind_on_malloc");
127   ParseFlag(str, &f->poison_heap, "poison_heap");
128   ParseFlag(str, &f->alloc_dealloc_mismatch, "alloc_dealloc_mismatch");
129   ParseFlag(str, &f->use_stack_depot, "use_stack_depot");
130   ParseFlag(str, &f->strict_memcmp, "strict_memcmp");
131 }
132 
133 static const char *asan_external_symbolizer;
134 
InitializeFlags(Flags * f,const char * env)135 void InitializeFlags(Flags *f, const char *env) {
136   internal_memset(f, 0, sizeof(*f));
137 
138   f->quarantine_size = (ASAN_LOW_MEMORY) ? 1UL << 26 : 1UL << 28;
139   f->symbolize = (asan_external_symbolizer != 0);
140   f->verbosity = 0;
141   f->redzone = ASAN_ALLOCATOR_VERSION == 2 ? 16 : (ASAN_LOW_MEMORY) ? 64 : 128;
142   f->debug = false;
143   f->report_globals = 1;
144   f->check_initialization_order = false;
145   f->malloc_context_size = kDeafultMallocContextSize;
146   f->replace_str = true;
147   f->replace_intrin = true;
148   f->mac_ignore_invalid_free = false;
149   f->use_fake_stack = true;
150   f->max_malloc_fill_size = 0;
151   f->exitcode = ASAN_DEFAULT_FAILURE_EXITCODE;
152   f->allow_user_poisoning = true;
153   f->sleep_before_dying = 0;
154   f->handle_segv = ASAN_NEEDS_SEGV;
155   f->use_sigaltstack = false;
156   f->check_malloc_usable_size = true;
157   f->unmap_shadow_on_exit = false;
158   f->abort_on_error = false;
159   f->print_stats = false;
160   f->print_legend = true;
161   f->atexit = false;
162   f->disable_core = (SANITIZER_WORDSIZE == 64);
163   f->strip_path_prefix = "";
164   f->allow_reexec = true;
165   f->print_full_thread_history = true;
166   f->log_path = 0;
167   f->fast_unwind_on_fatal = false;
168   f->fast_unwind_on_malloc = true;
169   f->poison_heap = true;
170   // Turn off alloc/dealloc mismatch checker on Mac for now.
171   // TODO(glider): Fix known issues and enable this back.
172   f->alloc_dealloc_mismatch = (ASAN_MAC == 0);;
173   f->use_stack_depot = true;  // Only affects allocator2.
174   f->strict_memcmp = true;
175 
176   // Override from compile definition.
177   ParseFlagsFromString(f, MaybeUseAsanDefaultOptionsCompileDefiniton());
178 
179   // Override from user-specified string.
180   ParseFlagsFromString(f, MaybeCallAsanDefaultOptions());
181   if (flags()->verbosity) {
182     Report("Using the defaults from __asan_default_options: %s\n",
183            MaybeCallAsanDefaultOptions());
184   }
185 
186   // Override from command line.
187   ParseFlagsFromString(f, env);
188 }
189 
190 // -------------------------- Globals --------------------- {{{1
191 int asan_inited;
192 bool asan_init_is_running;
193 void (*death_callback)(void);
194 
195 #if !ASAN_FIXED_MAPPING
196 uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;
197 #endif
198 
199 // -------------------------- Misc ---------------- {{{1
ShowStatsAndAbort()200 void ShowStatsAndAbort() {
201   __asan_print_accumulated_stats();
202   Die();
203 }
204 
205 // ---------------------- mmap -------------------- {{{1
206 // Reserve memory range [beg, end].
ReserveShadowMemoryRange(uptr beg,uptr end)207 static void ReserveShadowMemoryRange(uptr beg, uptr end) {
208   CHECK((beg % GetPageSizeCached()) == 0);
209   CHECK(((end + 1) % GetPageSizeCached()) == 0);
210   uptr size = end - beg + 1;
211   void *res = MmapFixedNoReserve(beg, size);
212   if (res != (void*)beg) {
213     Report("ReserveShadowMemoryRange failed while trying to map 0x%zx bytes. "
214            "Perhaps you're using ulimit -v\n", size);
215     Abort();
216   }
217 }
218 
219 // --------------- LowLevelAllocateCallbac ---------- {{{1
OnLowLevelAllocate(uptr ptr,uptr size)220 static void OnLowLevelAllocate(uptr ptr, uptr size) {
221   PoisonShadow(ptr, size, kAsanInternalHeapMagic);
222 }
223 
224 // -------------------------- Run-time entry ------------------- {{{1
225 // exported functions
226 #define ASAN_REPORT_ERROR(type, is_write, size)                     \
227 extern "C" NOINLINE INTERFACE_ATTRIBUTE                        \
228 void __asan_report_ ## type ## size(uptr addr);                \
229 void __asan_report_ ## type ## size(uptr addr) {               \
230   GET_CALLER_PC_BP_SP;                                              \
231   __asan_report_error(pc, bp, sp, addr, is_write, size);            \
232 }
233 
234 ASAN_REPORT_ERROR(load, false, 1)
235 ASAN_REPORT_ERROR(load, false, 2)
236 ASAN_REPORT_ERROR(load, false, 4)
237 ASAN_REPORT_ERROR(load, false, 8)
238 ASAN_REPORT_ERROR(load, false, 16)
239 ASAN_REPORT_ERROR(store, true, 1)
240 ASAN_REPORT_ERROR(store, true, 2)
241 ASAN_REPORT_ERROR(store, true, 4)
242 ASAN_REPORT_ERROR(store, true, 8)
243 ASAN_REPORT_ERROR(store, true, 16)
244 
245 #define ASAN_REPORT_ERROR_N(type, is_write)                    \
246 extern "C" NOINLINE INTERFACE_ATTRIBUTE                        \
247 void __asan_report_ ## type ## _n(uptr addr, uptr size);       \
248 void __asan_report_ ## type ## _n(uptr addr, uptr size) {      \
249   GET_CALLER_PC_BP_SP;                                         \
250   __asan_report_error(pc, bp, sp, addr, is_write, size);       \
251 }
252 
ASAN_REPORT_ERROR_N(load,false)253 ASAN_REPORT_ERROR_N(load, false)
254 ASAN_REPORT_ERROR_N(store, true)
255 
256 // Force the linker to keep the symbols for various ASan interface functions.
257 // We want to keep those in the executable in order to let the instrumented
258 // dynamic libraries access the symbol even if it is not used by the executable
259 // itself. This should help if the build system is removing dead code at link
260 // time.
261 static NOINLINE void force_interface_symbols() {
262   volatile int fake_condition = 0;  // prevent dead condition elimination.
263   // __asan_report_* functions are noreturn, so we need a switch to prevent
264   // the compiler from removing any of them.
265   switch (fake_condition) {
266     case 1: __asan_report_load1(0); break;
267     case 2: __asan_report_load2(0); break;
268     case 3: __asan_report_load4(0); break;
269     case 4: __asan_report_load8(0); break;
270     case 5: __asan_report_load16(0); break;
271     case 6: __asan_report_store1(0); break;
272     case 7: __asan_report_store2(0); break;
273     case 8: __asan_report_store4(0); break;
274     case 9: __asan_report_store8(0); break;
275     case 10: __asan_report_store16(0); break;
276     case 12: __asan_register_globals(0, 0); break;
277     case 13: __asan_unregister_globals(0, 0); break;
278     case 14: __asan_set_death_callback(0); break;
279     case 15: __asan_set_error_report_callback(0); break;
280     case 16: __asan_handle_no_return(); break;
281     case 17: __asan_address_is_poisoned(0); break;
282     case 18: __asan_get_allocated_size(0); break;
283     case 19: __asan_get_current_allocated_bytes(); break;
284     case 20: __asan_get_estimated_allocated_size(0); break;
285     case 21: __asan_get_free_bytes(); break;
286     case 22: __asan_get_heap_size(); break;
287     case 23: __asan_get_ownership(0); break;
288     case 24: __asan_get_unmapped_bytes(); break;
289     case 25: __asan_poison_memory_region(0, 0); break;
290     case 26: __asan_unpoison_memory_region(0, 0); break;
291     case 27: __asan_set_error_exit_code(0); break;
292     case 28: __asan_stack_free(0, 0, 0); break;
293     case 29: __asan_stack_malloc(0, 0); break;
294     case 30: __asan_before_dynamic_init(0, 0); break;
295     case 31: __asan_after_dynamic_init(); break;
296     case 32: __asan_poison_stack_memory(0, 0); break;
297     case 33: __asan_unpoison_stack_memory(0, 0); break;
298     case 34: __asan_region_is_poisoned(0, 0); break;
299     case 35: __asan_describe_address(0); break;
300   }
301 }
302 
asan_atexit()303 static void asan_atexit() {
304   Printf("AddressSanitizer exit stats:\n");
305   __asan_print_accumulated_stats();
306   // Print AsanMappingProfile.
307   for (uptr i = 0; i < kAsanMappingProfileSize; i++) {
308     if (AsanMappingProfile[i] == 0) continue;
309     Printf("asan_mapping.h:%zd -- %zd\n", i, AsanMappingProfile[i]);
310   }
311 }
312 
InitializeHighMemEnd()313 static void InitializeHighMemEnd() {
314 #if !ASAN_FIXED_MAPPING
315 #if SANITIZER_WORDSIZE == 64
316 # if defined(__powerpc64__)
317   // FIXME:
318   // On PowerPC64 we have two different address space layouts: 44- and 46-bit.
319   // We somehow need to figure our which one we are using now and choose
320   // one of 0x00000fffffffffffUL and 0x00003fffffffffffUL.
321   // Note that with 'ulimit -s unlimited' the stack is moved away from the top
322   // of the address space, so simply checking the stack address is not enough.
323   kHighMemEnd = (1ULL << 44) - 1;  // 0x00000fffffffffffUL
324 # else
325   kHighMemEnd = (1ULL << 47) - 1;  // 0x00007fffffffffffUL;
326 # endif
327 #else  // SANITIZER_WORDSIZE == 32
328   kHighMemEnd = (1ULL << 32) - 1;  // 0xffffffff;
329 #endif  // SANITIZER_WORDSIZE
330 #endif  // !ASAN_FIXED_MAPPING
331 }
332 
ProtectGap(uptr a,uptr size)333 static void ProtectGap(uptr a, uptr size) {
334   CHECK_EQ(a, (uptr)Mprotect(a, size));
335 }
336 
PrintAddressSpaceLayout()337 static void PrintAddressSpaceLayout() {
338   Printf("|| `[%p, %p]` || HighMem    ||\n",
339          (void*)kHighMemBeg, (void*)kHighMemEnd);
340   Printf("|| `[%p, %p]` || HighShadow ||\n",
341          (void*)kHighShadowBeg, (void*)kHighShadowEnd);
342   if (kMidMemBeg) {
343     Printf("|| `[%p, %p]` || ShadowGap3 ||\n",
344            (void*)kShadowGap3Beg, (void*)kShadowGap3End);
345     Printf("|| `[%p, %p]` || MidMem     ||\n",
346            (void*)kMidMemBeg, (void*)kMidMemEnd);
347     Printf("|| `[%p, %p]` || ShadowGap2 ||\n",
348            (void*)kShadowGap2Beg, (void*)kShadowGap2End);
349     Printf("|| `[%p, %p]` || MidShadow  ||\n",
350            (void*)kMidShadowBeg, (void*)kMidShadowEnd);
351   }
352   Printf("|| `[%p, %p]` || ShadowGap  ||\n",
353          (void*)kShadowGapBeg, (void*)kShadowGapEnd);
354   if (kLowShadowBeg) {
355     Printf("|| `[%p, %p]` || LowShadow  ||\n",
356            (void*)kLowShadowBeg, (void*)kLowShadowEnd);
357     Printf("|| `[%p, %p]` || LowMem     ||\n",
358            (void*)kLowMemBeg, (void*)kLowMemEnd);
359   }
360   Printf("MemToShadow(shadow): %p %p %p %p",
361          (void*)MEM_TO_SHADOW(kLowShadowBeg),
362          (void*)MEM_TO_SHADOW(kLowShadowEnd),
363          (void*)MEM_TO_SHADOW(kHighShadowBeg),
364          (void*)MEM_TO_SHADOW(kHighShadowEnd));
365   if (kMidMemBeg) {
366     Printf(" %p %p",
367            (void*)MEM_TO_SHADOW(kMidShadowBeg),
368            (void*)MEM_TO_SHADOW(kMidShadowEnd));
369   }
370   Printf("\n");
371   Printf("red_zone=%zu\n", (uptr)flags()->redzone);
372   Printf("malloc_context_size=%zu\n", (uptr)flags()->malloc_context_size);
373 
374   Printf("SHADOW_SCALE: %zx\n", (uptr)SHADOW_SCALE);
375   Printf("SHADOW_GRANULARITY: %zx\n", (uptr)SHADOW_GRANULARITY);
376   Printf("SHADOW_OFFSET: %zx\n", (uptr)SHADOW_OFFSET);
377   CHECK(SHADOW_SCALE >= 3 && SHADOW_SCALE <= 7);
378   if (kMidMemBeg)
379     CHECK(kMidShadowBeg > kLowShadowEnd &&
380           kMidMemBeg > kMidShadowEnd &&
381           kHighShadowBeg > kMidMemEnd);
382 }
383 
384 }  // namespace __asan
385 
386 // ---------------------- Interface ---------------- {{{1
387 using namespace __asan;  // NOLINT
388 
389 #if !SANITIZER_SUPPORTS_WEAK_HOOKS
390 extern "C" {
391 SANITIZER_WEAK_ATTRIBUTE SANITIZER_INTERFACE_ATTRIBUTE
__asan_default_options()392 const char* __asan_default_options() { return ""; }
393 }  // extern "C"
394 #endif
395 
__asan_set_error_exit_code(int exit_code)396 int NOINLINE __asan_set_error_exit_code(int exit_code) {
397   int old = flags()->exitcode;
398   flags()->exitcode = exit_code;
399   return old;
400 }
401 
__asan_handle_no_return()402 void NOINLINE __asan_handle_no_return() {
403   int local_stack;
404   AsanThread *curr_thread = asanThreadRegistry().GetCurrent();
405   CHECK(curr_thread);
406   uptr PageSize = GetPageSizeCached();
407   uptr top = curr_thread->stack_top();
408   uptr bottom = ((uptr)&local_stack - PageSize) & ~(PageSize-1);
409   PoisonShadow(bottom, top - bottom, 0);
410 }
411 
__asan_set_death_callback(void (* callback)(void))412 void NOINLINE __asan_set_death_callback(void (*callback)(void)) {
413   death_callback = callback;
414 }
415 
__asan_init()416 void __asan_init() {
417   if (asan_inited) return;
418   SanitizerToolName = "AddressSanitizer";
419   CHECK(!asan_init_is_running && "ASan init calls itself!");
420   asan_init_is_running = true;
421   InitializeHighMemEnd();
422 
423   // Make sure we are not statically linked.
424   AsanDoesNotSupportStaticLinkage();
425 
426   // Install tool-specific callbacks in sanitizer_common.
427   SetDieCallback(AsanDie);
428   SetCheckFailedCallback(AsanCheckFailed);
429   SetPrintfAndReportCallback(AppendToErrorMessageBuffer);
430 
431   // Check if external symbolizer is defined before parsing the flags.
432   asan_external_symbolizer = GetEnv("ASAN_SYMBOLIZER_PATH");
433   // Initialize flags. This must be done early, because most of the
434   // initialization steps look at flags().
435   const char *options = GetEnv("ASAN_OPTIONS");
436   InitializeFlags(flags(), options);
437   __sanitizer_set_report_path(flags()->log_path);
438 
439   if (flags()->verbosity && options) {
440     Report("Parsed ASAN_OPTIONS: %s\n", options);
441   }
442 
443   // Re-exec ourselves if we need to set additional env or command line args.
444   MaybeReexec();
445 
446   // Setup internal allocator callback.
447   SetLowLevelAllocateCallback(OnLowLevelAllocate);
448 
449   if (flags()->atexit) {
450     Atexit(asan_atexit);
451   }
452 
453   // interceptors
454   InitializeAsanInterceptors();
455 
456   ReplaceSystemMalloc();
457   ReplaceOperatorsNewAndDelete();
458 
459   uptr shadow_start = kLowShadowBeg;
460   if (kLowShadowBeg) shadow_start -= GetMmapGranularity();
461   uptr shadow_end = kHighShadowEnd;
462   bool full_shadow_is_available =
463       MemoryRangeIsAvailable(shadow_start, shadow_end);
464 
465 #if ASAN_LINUX && defined(__x86_64__) && !ASAN_FIXED_MAPPING
466   if (!full_shadow_is_available) {
467     kMidMemBeg = kLowMemEnd < 0x3000000000ULL ? 0x3000000000ULL : 0;
468     kMidMemEnd = kLowMemEnd < 0x3000000000ULL ? 0x4fffffffffULL : 0;
469   }
470 #endif
471 
472   if (flags()->verbosity)
473     PrintAddressSpaceLayout();
474 
475   if (flags()->disable_core) {
476     DisableCoreDumper();
477   }
478 
479   if (full_shadow_is_available) {
480     // mmap the low shadow plus at least one page at the left.
481     if (kLowShadowBeg)
482       ReserveShadowMemoryRange(shadow_start, kLowShadowEnd);
483     // mmap the high shadow.
484     ReserveShadowMemoryRange(kHighShadowBeg, kHighShadowEnd);
485     // protect the gap.
486     ProtectGap(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
487   } else if (kMidMemBeg &&
488       MemoryRangeIsAvailable(shadow_start, kMidMemBeg - 1) &&
489       MemoryRangeIsAvailable(kMidMemEnd + 1, shadow_end)) {
490     CHECK(kLowShadowBeg != kLowShadowEnd);
491     // mmap the low shadow plus at least one page at the left.
492     ReserveShadowMemoryRange(shadow_start, kLowShadowEnd);
493     // mmap the mid shadow.
494     ReserveShadowMemoryRange(kMidShadowBeg, kMidShadowEnd);
495     // mmap the high shadow.
496     ReserveShadowMemoryRange(kHighShadowBeg, kHighShadowEnd);
497     // protect the gaps.
498     ProtectGap(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
499     ProtectGap(kShadowGap2Beg, kShadowGap2End - kShadowGap2Beg + 1);
500     ProtectGap(kShadowGap3Beg, kShadowGap3End - kShadowGap3Beg + 1);
501   } else {
502     Report("Shadow memory range interleaves with an existing memory mapping. "
503            "ASan cannot proceed correctly. ABORTING.\n");
504     DumpProcessMap();
505     Die();
506   }
507 
508   InstallSignalHandlers();
509   // Start symbolizer process if necessary.
510   if (flags()->symbolize && asan_external_symbolizer &&
511       asan_external_symbolizer[0]) {
512     InitializeExternalSymbolizer(asan_external_symbolizer);
513   }
514 
515   // On Linux AsanThread::ThreadStart() calls malloc() that's why asan_inited
516   // should be set to 1 prior to initializing the threads.
517   asan_inited = 1;
518   asan_init_is_running = false;
519 
520   asanThreadRegistry().Init();
521   asanThreadRegistry().GetMain()->ThreadStart();
522   force_interface_symbols();  // no-op.
523 
524   InitializeAllocator();
525 
526   if (flags()->verbosity) {
527     Report("AddressSanitizer Init done\n");
528   }
529 }
530