libsanitizer/asan/asan_win_dynamic_runtime_thunk.cc

   1 //===-- asan_win_dynamic_runtime_thunk.cc ---------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is a part of AddressSanitizer, an address sanity checker.
   9 //
  10 // This file defines things that need to be present in the application modules
  11 // to interact with the ASan DLL runtime correctly and can't be implemented
  12 // using the default "import library" generated when linking the DLL RTL.
  13 //
  14 // This includes:
  15 //  - forwarding the detect_stack_use_after_return runtime option
  16 //  - working around deficiencies of the MD runtime
  17 //  - installing a custom SEH handler
  18 //
  19 //===----------------------------------------------------------------------===//
  20
  21 // Only compile this code when building asan_dynamic_runtime_thunk.lib
  22 // Using #ifdef rather than relying on Makefiles etc.
  23 // simplifies the build procedure.
  24 #ifdef ASAN_DYNAMIC_RUNTIME_THUNK
  25 #define WIN32_LEAN_AND_MEAN
  26 #include <windows.h>
  27
  28 // First, declare CRT sections we'll be using in this file
  29 #pragma section(".CRT$XID", long, read)  // NOLINT
  30 #pragma section(".CRT$XCAB", long, read)  // NOLINT
  31 #pragma section(".CRT$XTW", long, read)  // NOLINT
  32 #pragma section(".CRT$XTY", long, read)  // NOLINT
  33
  34 ////////////////////////////////////////////////////////////////////////////////
  35 // Define a copy of __asan_option_detect_stack_use_after_return that should be
  36 // used when linking an MD runtime with a set of object files on Windows.
  37 //
  38 // The ASan MD runtime dllexports '__asan_option_detect_stack_use_after_return',
  39 // so normally we would just dllimport it.  Unfortunately, the dllimport
  40 // attribute adds __imp_ prefix to the symbol name of a variable.
  41 // Since in general we don't know if a given TU is going to be used
  42 // with a MT or MD runtime and we don't want to use ugly __imp_ names on Windows
  43 // just to work around this issue, let's clone the variable that is constant
  44 // after initialization anyways.
  45 extern "C" {
  46 __declspec(dllimport) int __asan_should_detect_stack_use_after_return();
  47 int __asan_option_detect_stack_use_after_return =
  48     __asan_should_detect_stack_use_after_return();
  49
  50 __declspec(dllimport) void* __asan_get_shadow_memory_dynamic_address();
  51 void* __asan_shadow_memory_dynamic_address =
  52     __asan_get_shadow_memory_dynamic_address();
  53 }
  54
  55 ////////////////////////////////////////////////////////////////////////////////
  56 // For some reason, the MD CRT doesn't call the C/C++ terminators during on DLL
  57 // unload or on exit.  ASan relies on LLVM global_dtors to call
  58 // __asan_unregister_globals on these events, which unfortunately doesn't work
  59 // with the MD runtime, see PR22545 for the details.
  60 // To work around this, for each DLL we schedule a call to UnregisterGlobals
  61 // using atexit() that calls a small subset of C terminators
  62 // where LLVM global_dtors is placed.  Fingers crossed, no other C terminators
  63 // are there.
  64 extern "C" int __cdecl atexit(void (__cdecl *f)(void));
  65 extern "C" void __cdecl _initterm(void *a, void *b);
  66
  67 namespace {
  68 __declspec(allocate(".CRT$XTW")) void* before_global_dtors = 0;
  69 __declspec(allocate(".CRT$XTY")) void* after_global_dtors = 0;
  70
  71 void UnregisterGlobals() {
  72   _initterm(&before_global_dtors, &after_global_dtors);
  73 }
  74
  75 int ScheduleUnregisterGlobals() {
  76   return atexit(UnregisterGlobals);
  77 }
  78 }  // namespace
  79
  80 // We need to call 'atexit(UnregisterGlobals);' as early as possible, but after
  81 // atexit() is initialized (.CRT$XIC).  As this is executed before C++
  82 // initializers (think ctors for globals), UnregisterGlobals gets executed after
  83 // dtors for C++ globals.
  84 __declspec(allocate(".CRT$XID"))
  85 int (*__asan_schedule_unregister_globals)() = ScheduleUnregisterGlobals;
  86
  87 ////////////////////////////////////////////////////////////////////////////////
  88 // ASan SEH handling.
  89 // We need to set the ASan-specific SEH handler at the end of CRT initialization
  90 // of each module (see also asan_win.cc).
  91 extern "C" {
  92 __declspec(dllimport) int __asan_set_seh_filter();
  93 static int SetSEHFilter() { return __asan_set_seh_filter(); }
  94
  95 // Unfortunately, putting a pointer to __asan_set_seh_filter into
  96 // __asan_intercept_seh gets optimized out, so we have to use an extra function.
  97 __declspec(allocate(".CRT$XCAB")) int (*__asan_seh_interceptor)() =
  98     SetSEHFilter;
  99 }
 100
 101 #endif // ASAN_DYNAMIC_RUNTIME_THUNK