1//===-- asan_win.cpp
2//------------------------------------------------------===//>
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9//
10// This file is a part of AddressSanitizer, an address sanity checker.
11//
12// Windows-specific details.
13//===----------------------------------------------------------------------===//
14
15#include "sanitizer_common/sanitizer_platform.h"
16#if SANITIZER_WINDOWS
17# define WIN32_LEAN_AND_MEAN
18# include <stdlib.h>
19# include <windows.h>
20
21# include "asan_interceptors.h"
22# include "asan_internal.h"
23# include "asan_mapping.h"
24# include "asan_report.h"
25# include "asan_stack.h"
26# include "asan_thread.h"
27# include "sanitizer_common/sanitizer_libc.h"
28# include "sanitizer_common/sanitizer_mutex.h"
29# include "sanitizer_common/sanitizer_win.h"
30# include "sanitizer_common/sanitizer_win_defs.h"
31
32using namespace __asan;
33
34extern "C" {
35SANITIZER_INTERFACE_ATTRIBUTE
36int __asan_should_detect_stack_use_after_return() {
37 __asan_init();
38 return __asan_option_detect_stack_use_after_return;
39}
40
41SANITIZER_INTERFACE_ATTRIBUTE
42uptr __asan_get_shadow_memory_dynamic_address() {
43 __asan_init();
44 return __asan_shadow_memory_dynamic_address;
45}
46} // extern "C"
47
48// ---------------------- Windows-specific interceptors ---------------- {{{
49static LPTOP_LEVEL_EXCEPTION_FILTER default_seh_handler;
50static LPTOP_LEVEL_EXCEPTION_FILTER user_seh_handler;
51
52extern "C" SANITIZER_INTERFACE_ATTRIBUTE long __asan_unhandled_exception_filter(
53 EXCEPTION_POINTERS *info) {
54 EXCEPTION_RECORD *exception_record = info->ExceptionRecord;
55 CONTEXT *context = info->ContextRecord;
56
57 // FIXME: Handle EXCEPTION_STACK_OVERFLOW here.
58
59 SignalContext sig(exception_record, context);
60 ReportDeadlySignal(sig);
61 UNREACHABLE("returned from reporting deadly signal");
62}
63
64// Wrapper SEH Handler. If the exception should be handled by asan, we call
65// __asan_unhandled_exception_filter, otherwise, we execute the user provided
66// exception handler or the default.
67static long WINAPI SEHHandler(EXCEPTION_POINTERS *info) {
68 DWORD exception_code = info->ExceptionRecord->ExceptionCode;
69 if (__sanitizer::IsHandledDeadlyException(exception_code))
70 return __asan_unhandled_exception_filter(info);
71 if (user_seh_handler)
72 return user_seh_handler(info);
73 // Bubble out to the default exception filter.
74 if (default_seh_handler)
75 return default_seh_handler(info);
76 return EXCEPTION_CONTINUE_SEARCH;
77}
78
79INTERCEPTOR_WINAPI(LPTOP_LEVEL_EXCEPTION_FILTER, SetUnhandledExceptionFilter,
80 LPTOP_LEVEL_EXCEPTION_FILTER ExceptionFilter) {
81 CHECK(REAL(SetUnhandledExceptionFilter));
82 if (ExceptionFilter == &SEHHandler)
83 return REAL(SetUnhandledExceptionFilter)(ExceptionFilter);
84 // We record the user provided exception handler to be called for all the
85 // exceptions unhandled by asan.
86 Swap(ExceptionFilter, user_seh_handler);
87 return ExceptionFilter;
88}
89
90INTERCEPTOR_WINAPI(void, RtlRaiseException, EXCEPTION_RECORD *ExceptionRecord) {
91 CHECK(REAL(RtlRaiseException));
92 // This is a noreturn function, unless it's one of the exceptions raised to
93 // communicate with the debugger, such as the one from OutputDebugString.
94 if (ExceptionRecord->ExceptionCode != DBG_PRINTEXCEPTION_C)
95 __asan_handle_no_return();
96 REAL(RtlRaiseException)(ExceptionRecord);
97}
98
99INTERCEPTOR_WINAPI(void, RaiseException, void *a, void *b, void *c, void *d) {
100 CHECK(REAL(RaiseException));
101 __asan_handle_no_return();
102 REAL(RaiseException)(a, b, c, d);
103}
104
105#ifdef _WIN64
106
107INTERCEPTOR_WINAPI(EXCEPTION_DISPOSITION, __C_specific_handler,
108 _EXCEPTION_RECORD *a, void *b, _CONTEXT *c,
109 _DISPATCHER_CONTEXT *d) {
110 CHECK(REAL(__C_specific_handler));
111 __asan_handle_no_return();
112 return REAL(__C_specific_handler)(a, b, c, d);
113}
114
115#else
116
117INTERCEPTOR(int, _except_handler3, void *a, void *b, void *c, void *d) {
118 CHECK(REAL(_except_handler3));
119 __asan_handle_no_return();
120 return REAL(_except_handler3)(a, b, c, d);
121}
122
123#if ASAN_DYNAMIC
124// This handler is named differently in -MT and -MD CRTs.
125#define _except_handler4 _except_handler4_common
126#endif
127INTERCEPTOR(int, _except_handler4, void *a, void *b, void *c, void *d) {
128 CHECK(REAL(_except_handler4));
129 __asan_handle_no_return();
130 return REAL(_except_handler4)(a, b, c, d);
131}
132#endif
133
134struct ThreadStartParams {
135 thread_callback_t start_routine;
136 void *arg;
137};
138
139static thread_return_t THREAD_CALLING_CONV asan_thread_start(void *arg) {
140 AsanThread *t = (AsanThread *)arg;
141 SetCurrentThread(t);
142 t->ThreadStart(GetTid());
143
144 ThreadStartParams params;
145 t->GetStartData(params);
146
147 auto res = (*params.start_routine)(params.arg);
148 t->Destroy(); // POSIX calls this from TSD destructor.
149 return res;
150}
151
152INTERCEPTOR_WINAPI(HANDLE, CreateThread, LPSECURITY_ATTRIBUTES security,
153 SIZE_T stack_size, LPTHREAD_START_ROUTINE start_routine,
154 void *arg, DWORD thr_flags, DWORD *tid) {
155 // Strict init-order checking is thread-hostile.
156 if (flags()->strict_init_order)
157 StopInitOrderChecking();
158 GET_STACK_TRACE_THREAD;
159 // FIXME: The CreateThread interceptor is not the same as a pthread_create
160 // one. This is a bandaid fix for PR22025.
161 bool detached = false; // FIXME: how can we determine it on Windows?
162 u32 current_tid = GetCurrentTidOrInvalid();
163 ThreadStartParams params = {start_routine, arg};
164 AsanThread *t = AsanThread::Create(params, current_tid, &stack, detached);
165 return REAL(CreateThread)(security, stack_size, asan_thread_start, t,
166 thr_flags, tid);
167}
168
169// }}}
170
171namespace __asan {
172
173void InitializePlatformInterceptors() {
174 __interception::SetErrorReportCallback(Report);
175
176 // The interceptors were not designed to be removable, so we have to keep this
177 // module alive for the life of the process.
178 HMODULE pinned;
179 CHECK(GetModuleHandleExW(
180 GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_PIN,
181 (LPCWSTR)&InitializePlatformInterceptors, &pinned));
182
183 ASAN_INTERCEPT_FUNC(CreateThread);
184 ASAN_INTERCEPT_FUNC(SetUnhandledExceptionFilter);
185
186#ifdef _WIN64
187 ASAN_INTERCEPT_FUNC(__C_specific_handler);
188#else
189 ASAN_INTERCEPT_FUNC(_except_handler3);
190 ASAN_INTERCEPT_FUNC(_except_handler4);
191#endif
192
193 // Try to intercept kernel32!RaiseException, and if that fails, intercept
194 // ntdll!RtlRaiseException instead.
195 if (!::__interception::OverrideFunction("RaiseException",
196 (uptr)WRAP(RaiseException),
197 (uptr *)&REAL(RaiseException))) {
198 CHECK(::__interception::OverrideFunction("RtlRaiseException",
199 (uptr)WRAP(RtlRaiseException),
200 (uptr *)&REAL(RtlRaiseException)));
201 }
202}
203
204void InstallAtExitCheckLeaks() {}
205
206void InstallAtForkHandler() {}
207
208void AsanApplyToGlobals(globals_op_fptr op, const void *needle) {
209 UNIMPLEMENTED();
210}
211
212void FlushUnneededASanShadowMemory(uptr p, uptr size) {
213 // Only asan on 64-bit Windows supports committing shadow memory on demand.
214#if SANITIZER_WINDOWS64
215 // Since asan's mapping is compacting, the shadow chunk may be
216 // not page-aligned, so we only flush the page-aligned portion.
217 ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
218#endif
219}
220
221// ---------------------- TSD ---------------- {{{
222static bool tsd_key_inited = false;
223
224static __declspec(thread) void *fake_tsd = 0;
225
226// https://docs.microsoft.com/en-us/windows/desktop/api/winternl/ns-winternl-_teb
227// "[This structure may be altered in future versions of Windows. Applications
228// should use the alternate functions listed in this topic.]"
229typedef struct _TEB {
230 PVOID Reserved1[12];
231 // PVOID ThreadLocalStoragePointer; is here, at the last field in Reserved1.
232 PVOID ProcessEnvironmentBlock;
233 PVOID Reserved2[399];
234 BYTE Reserved3[1952];
235 PVOID TlsSlots[64];
236 BYTE Reserved4[8];
237 PVOID Reserved5[26];
238 PVOID ReservedForOle;
239 PVOID Reserved6[4];
240 PVOID TlsExpansionSlots;
241} TEB, *PTEB;
242
243constexpr size_t TEB_RESERVED_FIELDS_THREAD_LOCAL_STORAGE_OFFSET = 11;
244BOOL IsTlsInitialized() {
245 PTEB teb = (PTEB)NtCurrentTeb();
246 return teb->Reserved1[TEB_RESERVED_FIELDS_THREAD_LOCAL_STORAGE_OFFSET] !=
247 nullptr;
248}
249
250void AsanTSDInit(void (*destructor)(void *tsd)) {
251 // FIXME: we're ignoring the destructor for now.
252 tsd_key_inited = true;
253}
254
255void *AsanTSDGet() {
256 CHECK(tsd_key_inited);
257 return IsTlsInitialized() ? fake_tsd : nullptr;
258}
259
260void AsanTSDSet(void *tsd) {
261 CHECK(tsd_key_inited);
262 fake_tsd = tsd;
263}
264
265void PlatformTSDDtor(void *tsd) { AsanThread::TSDDtor(tsd); }
266// }}}
267
268// ---------------------- Various stuff ---------------- {{{
269uptr FindDynamicShadowStart() {
270 return MapDynamicShadow(MemToShadowSize(kHighMemEnd), ASAN_SHADOW_SCALE,
271 /*min_shadow_base_alignment*/ 0, kHighMemEnd);
272}
273
274void AsanCheckDynamicRTPrereqs() {}
275
276void AsanCheckIncompatibleRT() {}
277
278void AsanOnDeadlySignal(int, void *siginfo, void *context) { UNIMPLEMENTED(); }
279
280bool PlatformUnpoisonStacks() { return false; }
281
282#if SANITIZER_WINDOWS64
283// Exception handler for dealing with shadow memory.
284static LONG CALLBACK
285ShadowExceptionHandler(PEXCEPTION_POINTERS exception_pointers) {
286 uptr page_size = GetPageSizeCached();
287 // Only handle access violations.
288 if (exception_pointers->ExceptionRecord->ExceptionCode !=
289 EXCEPTION_ACCESS_VIOLATION ||
290 exception_pointers->ExceptionRecord->NumberParameters < 2) {
291 __asan_handle_no_return();
292 return EXCEPTION_CONTINUE_SEARCH;
293 }
294
295 // Only handle access violations that land within the shadow memory.
296 uptr addr =
297 (uptr)(exception_pointers->ExceptionRecord->ExceptionInformation[1]);
298
299 // Check valid shadow range.
300 if (!AddrIsInShadow(addr)) {
301 __asan_handle_no_return();
302 return EXCEPTION_CONTINUE_SEARCH;
303 }
304
305 // This is an access violation while trying to read from the shadow. Commit
306 // the relevant page and let execution continue.
307
308 // Determine the address of the page that is being accessed.
309 uptr page = RoundDownTo(addr, page_size);
310
311 // Commit the page.
312 uptr result =
313 (uptr)::VirtualAlloc((LPVOID)page, page_size, MEM_COMMIT, PAGE_READWRITE);
314 if (result != page)
315 return EXCEPTION_CONTINUE_SEARCH;
316
317 // The page mapping succeeded, so continue execution as usual.
318 return EXCEPTION_CONTINUE_EXECUTION;
319}
320
321#endif
322
323void InitializePlatformExceptionHandlers() {
324#if SANITIZER_WINDOWS64
325 // On Win64, we map memory on demand with access violation handler.
326 // Install our exception handler.
327 CHECK(AddVectoredExceptionHandler(TRUE, &ShadowExceptionHandler));
328#endif
329}
330
331bool IsSystemHeapAddress(uptr addr) {
332 return ::HeapValidate(GetProcessHeap(), 0, (void *)addr) != FALSE;
333}
334
335// We want to install our own exception handler (EH) to print helpful reports
336// on access violations and whatnot. Unfortunately, the CRT initializers assume
337// they are run before any user code and drop any previously-installed EHs on
338// the floor, so we can't install our handler inside __asan_init.
339// (See crt0dat.c in the CRT sources for the details)
340//
341// Things get even more complicated with the dynamic runtime, as it finishes its
342// initialization before the .exe module CRT begins to initialize.
343//
344// For the static runtime (-MT), it's enough to put a callback to
345// __asan_set_seh_filter in the last section for C initializers.
346//
347// For the dynamic runtime (-MD), we want link the same
348// asan_dynamic_runtime_thunk.lib to all the modules, thus __asan_set_seh_filter
349// will be called for each instrumented module. This ensures that at least one
350// __asan_set_seh_filter call happens after the .exe module CRT is initialized.
351extern "C" SANITIZER_INTERFACE_ATTRIBUTE int __asan_set_seh_filter() {
352 // We should only store the previous handler if it's not our own handler in
353 // order to avoid loops in the EH chain.
354 auto prev_seh_handler = SetUnhandledExceptionFilter(SEHHandler);
355 if (prev_seh_handler != &SEHHandler)
356 default_seh_handler = prev_seh_handler;
357 return 0;
358}
359
360bool HandleDlopenInit() {
361 // Not supported on this platform.
362 static_assert(!SANITIZER_SUPPORTS_INIT_FOR_DLOPEN,
363 "Expected SANITIZER_SUPPORTS_INIT_FOR_DLOPEN to be false");
364 return false;
365}
366
367#if !ASAN_DYNAMIC
368// The CRT runs initializers in this order:
369// - C initializers, from XIA to XIZ
370// - C++ initializers, from XCA to XCZ
371// Prior to 2015, the CRT set the unhandled exception filter at priority XIY,
372// near the end of C initialization. Starting in 2015, it was moved to the
373// beginning of C++ initialization. We set our priority to XCAB to run
374// immediately after the CRT runs. This way, our exception filter is called
375// first and we can delegate to their filter if appropriate.
376#pragma section(".CRT$XCAB", long, read)
377__declspec(allocate(".CRT$XCAB")) int (*__intercept_seh)() =
378 __asan_set_seh_filter;
379
380// Piggyback on the TLS initialization callback directory to initialize asan as
381// early as possible. Initializers in .CRT$XL* are called directly by ntdll,
382// which run before the CRT. Users also add code to .CRT$XLC, so it's important
383// to run our initializers first.
384static void NTAPI asan_thread_init(void *module, DWORD reason, void *reserved) {
385 if (reason == DLL_PROCESS_ATTACH)
386 __asan_init();
387}
388
389#pragma section(".CRT$XLAB", long, read)
390__declspec(allocate(".CRT$XLAB")) void(NTAPI *__asan_tls_init)(
391 void *, unsigned long, void *) = asan_thread_init;
392#endif
393
394static void NTAPI asan_thread_exit(void *module, DWORD reason, void *reserved) {
395 if (reason == DLL_THREAD_DETACH) {
396 // Unpoison the thread's stack because the memory may be re-used.
397 NT_TIB *tib = (NT_TIB *)NtCurrentTeb();
398 uptr stackSize = (uptr)tib->StackBase - (uptr)tib->StackLimit;
399 __asan_unpoison_memory_region(tib->StackLimit, stackSize);
400 }
401}
402
403#pragma section(".CRT$XLY", long, read)
404__declspec(allocate(".CRT$XLY")) void(NTAPI *__asan_tls_exit)(
405 void *, unsigned long, void *) = asan_thread_exit;
406
407WIN_FORCE_LINK(__asan_dso_reg_hook)
408
409// }}}
410} // namespace __asan
411
412#endif // SANITIZER_WINDOWS
413

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