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 ---------------- {{{
269void *AsanDoesNotSupportStaticLinkage() { return 0; }
270
271uptr FindDynamicShadowStart() {
272  return MapDynamicShadow(MemToShadowSize(kHighMemEnd), ASAN_SHADOW_SCALE,
273                          /*min_shadow_base_alignment*/ 0, kHighMemEnd);
274}
275
276void AsanCheckDynamicRTPrereqs() {}
277
278void AsanCheckIncompatibleRT() {}
279
280void AsanOnDeadlySignal(int, void *siginfo, void *context) { UNIMPLEMENTED(); }
281
282bool PlatformUnpoisonStacks() { return false; }
283
284#if SANITIZER_WINDOWS64
285// Exception handler for dealing with shadow memory.
286static LONG CALLBACK
287ShadowExceptionHandler(PEXCEPTION_POINTERS exception_pointers) {
288  uptr page_size = GetPageSizeCached();
289  // Only handle access violations.
290  if (exception_pointers->ExceptionRecord->ExceptionCode !=
291          EXCEPTION_ACCESS_VIOLATION ||
292      exception_pointers->ExceptionRecord->NumberParameters < 2) {
293    __asan_handle_no_return();
294    return EXCEPTION_CONTINUE_SEARCH;
295  }
296
297  // Only handle access violations that land within the shadow memory.
298  uptr addr =
299      (uptr)(exception_pointers->ExceptionRecord->ExceptionInformation[1]);
300
301  // Check valid shadow range.
302  if (!AddrIsInShadow(addr)) {
303    __asan_handle_no_return();
304    return EXCEPTION_CONTINUE_SEARCH;
305  }
306
307  // This is an access violation while trying to read from the shadow. Commit
308  // the relevant page and let execution continue.
309
310  // Determine the address of the page that is being accessed.
311  uptr page = RoundDownTo(addr, page_size);
312
313  // Commit the page.
314  uptr result =
315      (uptr)::VirtualAlloc((LPVOID)page, page_size, MEM_COMMIT, PAGE_READWRITE);
316  if (result != page)
317    return EXCEPTION_CONTINUE_SEARCH;
318
319  // The page mapping succeeded, so continue execution as usual.
320  return EXCEPTION_CONTINUE_EXECUTION;
321}
322
323#endif
324
325void InitializePlatformExceptionHandlers() {
326#if SANITIZER_WINDOWS64
327  // On Win64, we map memory on demand with access violation handler.
328  // Install our exception handler.
329  CHECK(AddVectoredExceptionHandler(TRUE, &ShadowExceptionHandler));
330#endif
331}
332
333bool IsSystemHeapAddress(uptr addr) {
334  return ::HeapValidate(GetProcessHeap(), 0, (void *)addr) != FALSE;
335}
336
337// We want to install our own exception handler (EH) to print helpful reports
338// on access violations and whatnot.  Unfortunately, the CRT initializers assume
339// they are run before any user code and drop any previously-installed EHs on
340// the floor, so we can't install our handler inside __asan_init.
341// (See crt0dat.c in the CRT sources for the details)
342//
343// Things get even more complicated with the dynamic runtime, as it finishes its
344// initialization before the .exe module CRT begins to initialize.
345//
346// For the static runtime (-MT), it's enough to put a callback to
347// __asan_set_seh_filter in the last section for C initializers.
348//
349// For the dynamic runtime (-MD), we want link the same
350// asan_dynamic_runtime_thunk.lib to all the modules, thus __asan_set_seh_filter
351// will be called for each instrumented module.  This ensures that at least one
352// __asan_set_seh_filter call happens after the .exe module CRT is initialized.
353extern "C" SANITIZER_INTERFACE_ATTRIBUTE int __asan_set_seh_filter() {
354  // We should only store the previous handler if it's not our own handler in
355  // order to avoid loops in the EH chain.
356  auto prev_seh_handler = SetUnhandledExceptionFilter(SEHHandler);
357  if (prev_seh_handler != &SEHHandler)
358    default_seh_handler = prev_seh_handler;
359  return 0;
360}
361
362bool HandleDlopenInit() {
363  // Not supported on this platform.
364  static_assert(!SANITIZER_SUPPORTS_INIT_FOR_DLOPEN,
365                "Expected SANITIZER_SUPPORTS_INIT_FOR_DLOPEN to be false");
366  return false;
367}
368
369#if !ASAN_DYNAMIC
370// The CRT runs initializers in this order:
371// - C initializers, from XIA to XIZ
372// - C++ initializers, from XCA to XCZ
373// Prior to 2015, the CRT set the unhandled exception filter at priority XIY,
374// near the end of C initialization. Starting in 2015, it was moved to the
375// beginning of C++ initialization. We set our priority to XCAB to run
376// immediately after the CRT runs. This way, our exception filter is called
377// first and we can delegate to their filter if appropriate.
378#pragma section(".CRT$XCAB", long, read)
379__declspec(allocate(".CRT$XCAB")) int (*__intercept_seh)() =
380    __asan_set_seh_filter;
381
382// Piggyback on the TLS initialization callback directory to initialize asan as
383// early as possible. Initializers in .CRT$XL* are called directly by ntdll,
384// which run before the CRT. Users also add code to .CRT$XLC, so it's important
385// to run our initializers first.
386static void NTAPI asan_thread_init(void *module, DWORD reason, void *reserved) {
387  if (reason == DLL_PROCESS_ATTACH)
388    __asan_init();
389}
390
391#pragma section(".CRT$XLAB", long, read)
392__declspec(allocate(".CRT$XLAB")) void(NTAPI *__asan_tls_init)(
393    void *, unsigned long, void *) = asan_thread_init;
394#endif
395
396static void NTAPI asan_thread_exit(void *module, DWORD reason, void *reserved) {
397  if (reason == DLL_THREAD_DETACH) {
398    // Unpoison the thread's stack because the memory may be re-used.
399    NT_TIB *tib = (NT_TIB *)NtCurrentTeb();
400    uptr stackSize = (uptr)tib->StackBase - (uptr)tib->StackLimit;
401    __asan_unpoison_memory_region(tib->StackLimit, stackSize);
402  }
403}
404
405#pragma section(".CRT$XLY", long, read)
406__declspec(allocate(".CRT$XLY")) void(NTAPI *__asan_tls_exit)(
407    void *, unsigned long, void *) = asan_thread_exit;
408
409WIN_FORCE_LINK(__asan_dso_reg_hook)
410
411// }}}
412}  // namespace __asan
413
414#endif  // SANITIZER_WINDOWS
415