1 //===-- asan_win_dynamic_runtime_thunk.cpp --------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file is a part of AddressSanitizer, an address sanity checker. 10 // 11 // This file defines things that need to be present in the application modules 12 // to interact with the ASan DLL runtime correctly and can't be implemented 13 // using the default "import library" generated when linking the DLL RTL. 14 // 15 // This includes: 16 // - creating weak aliases to default implementation imported from asan dll. 17 // - forwarding the detect_stack_use_after_return runtime option 18 // - working around deficiencies of the MD runtime 19 // - installing a custom SEH handler 20 // 21 //===----------------------------------------------------------------------===// 22 23 #ifdef SANITIZER_DYNAMIC_RUNTIME_THUNK 24 #define SANITIZER_IMPORT_INTERFACE 1 25 #include "sanitizer_common/sanitizer_win_defs.h" 26 #define WIN32_LEAN_AND_MEAN 27 #include <windows.h> 28 29 // Define weak alias for all weak functions imported from asan dll. 30 #define INTERFACE_FUNCTION(Name) 31 #define INTERFACE_WEAK_FUNCTION(Name) WIN_WEAK_IMPORT_DEF(Name) 32 #include "asan_interface.inc" 33 34 // First, declare CRT sections we'll be using in this file 35 #pragma section(".CRT$XIB", long, read) 36 #pragma section(".CRT$XID", long, read) 37 #pragma section(".CRT$XCAB", long, read) 38 #pragma section(".CRT$XTW", long, read) 39 #pragma section(".CRT$XTY", long, read) 40 #pragma section(".CRT$XLAB", long, read) 41 42 //////////////////////////////////////////////////////////////////////////////// 43 // Define a copy of __asan_option_detect_stack_use_after_return that should be 44 // used when linking an MD runtime with a set of object files on Windows. 45 // 46 // The ASan MD runtime dllexports '__asan_option_detect_stack_use_after_return', 47 // so normally we would just dllimport it. Unfortunately, the dllimport 48 // attribute adds __imp_ prefix to the symbol name of a variable. 49 // Since in general we don't know if a given TU is going to be used 50 // with a MT or MD runtime and we don't want to use ugly __imp_ names on Windows 51 // just to work around this issue, let's clone the variable that is constant 52 // after initialization anyways. 53 extern "C" { 54 __declspec(dllimport) int __asan_should_detect_stack_use_after_return(); 55 int __asan_option_detect_stack_use_after_return; 56 57 __declspec(dllimport) void* __asan_get_shadow_memory_dynamic_address(); 58 void* __asan_shadow_memory_dynamic_address; 59 } 60 61 static int InitializeClonedVariables() { 62 __asan_option_detect_stack_use_after_return = 63 __asan_should_detect_stack_use_after_return(); 64 __asan_shadow_memory_dynamic_address = 65 __asan_get_shadow_memory_dynamic_address(); 66 return 0; 67 } 68 69 static void NTAPI asan_thread_init(void *mod, unsigned long reason, 70 void *reserved) { 71 if (reason == DLL_PROCESS_ATTACH) InitializeClonedVariables(); 72 } 73 74 // Our cloned variables must be initialized before C/C++ constructors. If TLS 75 // is used, our .CRT$XLAB initializer will run first. If not, our .CRT$XIB 76 // initializer is needed as a backup. 77 __declspec(allocate(".CRT$XIB")) int (*__asan_initialize_cloned_variables)() = 78 InitializeClonedVariables; 79 __declspec(allocate(".CRT$XLAB")) void (NTAPI *__asan_tls_init)(void *, 80 unsigned long, void *) = asan_thread_init; 81 82 //////////////////////////////////////////////////////////////////////////////// 83 // For some reason, the MD CRT doesn't call the C/C++ terminators during on DLL 84 // unload or on exit. ASan relies on LLVM global_dtors to call 85 // __asan_unregister_globals on these events, which unfortunately doesn't work 86 // with the MD runtime, see PR22545 for the details. 87 // To work around this, for each DLL we schedule a call to UnregisterGlobals 88 // using atexit() that calls a small subset of C terminators 89 // where LLVM global_dtors is placed. Fingers crossed, no other C terminators 90 // are there. 91 extern "C" int __cdecl atexit(void (__cdecl *f)(void)); 92 extern "C" void __cdecl _initterm(void *a, void *b); 93 94 namespace { 95 __declspec(allocate(".CRT$XTW")) void* before_global_dtors = 0; 96 __declspec(allocate(".CRT$XTY")) void* after_global_dtors = 0; 97 98 void UnregisterGlobals() { 99 _initterm(&before_global_dtors, &after_global_dtors); 100 } 101 102 int ScheduleUnregisterGlobals() { 103 return atexit(UnregisterGlobals); 104 } 105 } // namespace 106 107 // We need to call 'atexit(UnregisterGlobals);' as early as possible, but after 108 // atexit() is initialized (.CRT$XIC). As this is executed before C++ 109 // initializers (think ctors for globals), UnregisterGlobals gets executed after 110 // dtors for C++ globals. 111 __declspec(allocate(".CRT$XID")) 112 int (*__asan_schedule_unregister_globals)() = ScheduleUnregisterGlobals; 113 114 //////////////////////////////////////////////////////////////////////////////// 115 // ASan SEH handling. 116 // We need to set the ASan-specific SEH handler at the end of CRT initialization 117 // of each module (see also asan_win.cpp). 118 extern "C" { 119 __declspec(dllimport) int __asan_set_seh_filter(); 120 static int SetSEHFilter() { return __asan_set_seh_filter(); } 121 122 // Unfortunately, putting a pointer to __asan_set_seh_filter into 123 // __asan_intercept_seh gets optimized out, so we have to use an extra function. 124 __declspec(allocate(".CRT$XCAB")) int (*__asan_seh_interceptor)() = 125 SetSEHFilter; 126 } 127 128 WIN_FORCE_LINK(__asan_dso_reg_hook) 129 130 #endif // SANITIZER_DYNAMIC_RUNTIME_THUNK 131