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.
53extern "C" {
54__declspec(dllimport) int __asan_should_detect_stack_use_after_return();
55int __asan_option_detect_stack_use_after_return;
56
57__declspec(dllimport) void* __asan_get_shadow_memory_dynamic_address();
58void* __asan_shadow_memory_dynamic_address;
59}
60
61static 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
69static 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.
91extern "C" int __cdecl atexit(void (__cdecl *f)(void));
92extern "C" void __cdecl _initterm(void *a, void *b);
93
94namespace {
95__declspec(allocate(".CRT$XTW")) void* before_global_dtors = 0;
96__declspec(allocate(".CRT$XTY")) void* after_global_dtors = 0;
97
98void UnregisterGlobals() {
99 _initterm(&before_global_dtors, &after_global_dtors);
100}
101
102int 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"))
112int (*__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).
118extern "C" {
119__declspec(dllimport) int __asan_set_seh_filter();
120static 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
128WIN_FORCE_LINK(__asan_dso_reg_hook)
129
130#endif // SANITIZER_DYNAMIC_RUNTIME_THUNK
131

source code of compiler-rt/lib/asan/asan_win_dynamic_runtime_thunk.cpp