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 return res;
149}
150
151INTERCEPTOR_WINAPI(HANDLE, CreateThread, LPSECURITY_ATTRIBUTES security,
152 SIZE_T stack_size, LPTHREAD_START_ROUTINE start_routine,
153 void *arg, DWORD thr_flags, DWORD *tid) {
154 // Strict init-order checking is thread-hostile.
155 if (flags()->strict_init_order)
156 StopInitOrderChecking();
157 GET_STACK_TRACE_THREAD;
158 // FIXME: The CreateThread interceptor is not the same as a pthread_create
159 // one. This is a bandaid fix for PR22025.
160 bool detached = false; // FIXME: how can we determine it on Windows?
161 u32 current_tid = GetCurrentTidOrInvalid();
162 ThreadStartParams params = {start_routine, arg};
163 AsanThread *t = AsanThread::Create(params, current_tid, &stack, detached);
164 return REAL(CreateThread)(security, stack_size, asan_thread_start, t,
165 thr_flags, tid);
166}
167
168INTERCEPTOR_WINAPI(void, ExitThread, DWORD dwExitCode) {
169 AsanThread *t = (AsanThread *)__asan::GetCurrentThread();
170 if (t)
171 t->Destroy();
172 REAL(ExitThread)(dwExitCode);
173}
174
175// }}}
176
177namespace __asan {
178
179void InitializePlatformInterceptors() {
180 __interception::SetErrorReportCallback(Report);
181
182 // The interceptors were not designed to be removable, so we have to keep this
183 // module alive for the life of the process.
184 HMODULE pinned;
185 CHECK(GetModuleHandleExW(
186 GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_PIN,
187 (LPCWSTR)&InitializePlatformInterceptors, &pinned));
188
189 ASAN_INTERCEPT_FUNC(CreateThread);
190 ASAN_INTERCEPT_FUNC(ExitThread);
191 ASAN_INTERCEPT_FUNC(SetUnhandledExceptionFilter);
192
193#ifdef _WIN64
194 ASAN_INTERCEPT_FUNC(__C_specific_handler);
195#else
196 ASAN_INTERCEPT_FUNC(_except_handler3);
197 ASAN_INTERCEPT_FUNC(_except_handler4);
198#endif
199
200 // Try to intercept kernel32!RaiseException, and if that fails, intercept
201 // ntdll!RtlRaiseException instead.
202 if (!::__interception::OverrideFunction("RaiseException",
203 (uptr)WRAP(RaiseException),
204 (uptr *)&REAL(RaiseException))) {
205 CHECK(::__interception::OverrideFunction("RtlRaiseException",
206 (uptr)WRAP(RtlRaiseException),
207 (uptr *)&REAL(RtlRaiseException)));
208 }
209}
210
211void InstallAtExitCheckLeaks() {}
212
213void InstallAtForkHandler() {}
214
215void AsanApplyToGlobals(globals_op_fptr op, const void *needle) {
216 UNIMPLEMENTED();
217}
218
219void FlushUnneededASanShadowMemory(uptr p, uptr size) {
220 // Only asan on 64-bit Windows supports committing shadow memory on demand.
221#if SANITIZER_WINDOWS64
222 // Since asan's mapping is compacting, the shadow chunk may be
223 // not page-aligned, so we only flush the page-aligned portion.
224 ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
225#endif
226}
227
228// ---------------------- TSD ---------------- {{{
229static bool tsd_key_inited = false;
230
231static __declspec(thread) void *fake_tsd = 0;
232
233// https://docs.microsoft.com/en-us/windows/desktop/api/winternl/ns-winternl-_teb
234// "[This structure may be altered in future versions of Windows. Applications
235// should use the alternate functions listed in this topic.]"
236typedef struct _TEB {
237 PVOID Reserved1[12];
238 // PVOID ThreadLocalStoragePointer; is here, at the last field in Reserved1.
239 PVOID ProcessEnvironmentBlock;
240 PVOID Reserved2[399];
241 BYTE Reserved3[1952];
242 PVOID TlsSlots[64];
243 BYTE Reserved4[8];
244 PVOID Reserved5[26];
245 PVOID ReservedForOle;
246 PVOID Reserved6[4];
247 PVOID TlsExpansionSlots;
248} TEB, *PTEB;
249
250constexpr size_t TEB_RESERVED_FIELDS_THREAD_LOCAL_STORAGE_OFFSET = 11;
251BOOL IsTlsInitialized() {
252 PTEB teb = (PTEB)NtCurrentTeb();
253 return teb->Reserved1[TEB_RESERVED_FIELDS_THREAD_LOCAL_STORAGE_OFFSET] !=
254 nullptr;
255}
256
257void AsanTSDInit(void (*destructor)(void *tsd)) {
258 // FIXME: we're ignoring the destructor for now.
259 tsd_key_inited = true;
260}
261
262void *AsanTSDGet() {
263 CHECK(tsd_key_inited);
264 return IsTlsInitialized() ? fake_tsd : nullptr;
265}
266
267void AsanTSDSet(void *tsd) {
268 CHECK(tsd_key_inited);
269 fake_tsd = tsd;
270}
271
272void PlatformTSDDtor(void *tsd) { AsanThread::TSDDtor(tsd); }
273// }}}
274
275// ---------------------- Various stuff ---------------- {{{
276uptr FindDynamicShadowStart() {
277 return MapDynamicShadow(MemToShadowSize(kHighMemEnd), ASAN_SHADOW_SCALE,
278 /*min_shadow_base_alignment*/ 0, kHighMemEnd,
279 GetMmapGranularity());
280}
281
282// Not used
283void TryReExecWithoutASLR() {}
284
285void AsanCheckDynamicRTPrereqs() {}
286
287void AsanCheckIncompatibleRT() {}
288
289void AsanOnDeadlySignal(int, void *siginfo, void *context) { UNIMPLEMENTED(); }
290
291bool PlatformUnpoisonStacks() { return false; }
292
293#if SANITIZER_WINDOWS64
294// Exception handler for dealing with shadow memory.
295static LONG CALLBACK
296ShadowExceptionHandler(PEXCEPTION_POINTERS exception_pointers) {
297 uptr page_size = GetPageSizeCached();
298 // Only handle access violations.
299 if (exception_pointers->ExceptionRecord->ExceptionCode !=
300 EXCEPTION_ACCESS_VIOLATION ||
301 exception_pointers->ExceptionRecord->NumberParameters < 2) {
302 __asan_handle_no_return();
303 return EXCEPTION_CONTINUE_SEARCH;
304 }
305
306 // Only handle access violations that land within the shadow memory.
307 uptr addr =
308 (uptr)(exception_pointers->ExceptionRecord->ExceptionInformation[1]);
309
310 // Check valid shadow range.
311 if (!AddrIsInShadow(addr)) {
312 __asan_handle_no_return();
313 return EXCEPTION_CONTINUE_SEARCH;
314 }
315
316 // This is an access violation while trying to read from the shadow. Commit
317 // the relevant page and let execution continue.
318
319 // Determine the address of the page that is being accessed.
320 uptr page = RoundDownTo(addr, page_size);
321
322 // Commit the page.
323 uptr result =
324 (uptr)::VirtualAlloc((LPVOID)page, page_size, MEM_COMMIT, PAGE_READWRITE);
325 if (result != page)
326 return EXCEPTION_CONTINUE_SEARCH;
327
328 // The page mapping succeeded, so continue execution as usual.
329 return EXCEPTION_CONTINUE_EXECUTION;
330}
331
332#endif
333
334void InitializePlatformExceptionHandlers() {
335#if SANITIZER_WINDOWS64
336 // On Win64, we map memory on demand with access violation handler.
337 // Install our exception handler.
338 CHECK(AddVectoredExceptionHandler(TRUE, &ShadowExceptionHandler));
339#endif
340}
341
342bool IsSystemHeapAddress(uptr addr) {
343 return ::HeapValidate(GetProcessHeap(), 0, (void *)addr) != FALSE;
344}
345
346// We want to install our own exception handler (EH) to print helpful reports
347// on access violations and whatnot. Unfortunately, the CRT initializers assume
348// they are run before any user code and drop any previously-installed EHs on
349// the floor, so we can't install our handler inside __asan_init.
350// (See crt0dat.c in the CRT sources for the details)
351//
352// Things get even more complicated with the dynamic runtime, as it finishes its
353// initialization before the .exe module CRT begins to initialize.
354//
355// For the static runtime (-MT), it's enough to put a callback to
356// __asan_set_seh_filter in the last section for C initializers.
357//
358// For the dynamic runtime (-MD), we want link the same
359// asan_dynamic_runtime_thunk.lib to all the modules, thus __asan_set_seh_filter
360// will be called for each instrumented module. This ensures that at least one
361// __asan_set_seh_filter call happens after the .exe module CRT is initialized.
362extern "C" SANITIZER_INTERFACE_ATTRIBUTE int __asan_set_seh_filter() {
363 // We should only store the previous handler if it's not our own handler in
364 // order to avoid loops in the EH chain.
365 auto prev_seh_handler = SetUnhandledExceptionFilter(SEHHandler);
366 if (prev_seh_handler != &SEHHandler)
367 default_seh_handler = prev_seh_handler;
368 return 0;
369}
370
371bool HandleDlopenInit() {
372 // Not supported on this platform.
373 static_assert(!SANITIZER_SUPPORTS_INIT_FOR_DLOPEN,
374 "Expected SANITIZER_SUPPORTS_INIT_FOR_DLOPEN to be false");
375 return false;
376}
377
378#if !ASAN_DYNAMIC
379// The CRT runs initializers in this order:
380// - C initializers, from XIA to XIZ
381// - C++ initializers, from XCA to XCZ
382// Prior to 2015, the CRT set the unhandled exception filter at priority XIY,
383// near the end of C initialization. Starting in 2015, it was moved to the
384// beginning of C++ initialization. We set our priority to XCAB to run
385// immediately after the CRT runs. This way, our exception filter is called
386// first and we can delegate to their filter if appropriate.
387#pragma section(".CRT$XCAB", long, read)
388__declspec(allocate(".CRT$XCAB")) int (*__intercept_seh)() =
389 __asan_set_seh_filter;
390
391// Piggyback on the TLS initialization callback directory to initialize asan as
392// early as possible. Initializers in .CRT$XL* are called directly by ntdll,
393// which run before the CRT. Users also add code to .CRT$XLC, so it's important
394// to run our initializers first.
395static void NTAPI asan_thread_init(void *module, DWORD reason, void *reserved) {
396 if (reason == DLL_PROCESS_ATTACH)
397 __asan_init();
398}
399
400#pragma section(".CRT$XLAB", long, read)
401__declspec(allocate(".CRT$XLAB")) void(NTAPI *__asan_tls_init)(
402 void *, unsigned long, void *) = asan_thread_init;
403#endif
404
405static void NTAPI asan_thread_exit(void *module, DWORD reason, void *reserved) {
406 if (reason == DLL_THREAD_DETACH) {
407 // Unpoison the thread's stack because the memory may be re-used.
408 NT_TIB *tib = (NT_TIB *)NtCurrentTeb();
409 uptr stackSize = (uptr)tib->StackBase - (uptr)tib->StackLimit;
410 __asan_unpoison_memory_region(tib->StackLimit, stackSize);
411 }
412}
413
414#pragma section(".CRT$XLY", long, read)
415__declspec(allocate(".CRT$XLY")) void(NTAPI *__asan_tls_exit)(
416 void *, unsigned long, void *) = asan_thread_exit;
417
418WIN_FORCE_LINK(__asan_dso_reg_hook)
419
420// }}}
421} // namespace __asan
422
423#endif // SANITIZER_WINDOWS
424