build/build-clang/unpoison-thread-stacks_clang_10.patch

   1 [winasan] Unpoison the stack in NtTerminateThread
   2
   3 In long-running builds we've seen some ASan complaints during thread creation
   4 that we suspect are due to leftover poisoning from previous threads whose stacks
   5 occupied that memory. This patch adds a hook that unpoisons the stack just
   6 before the NtTerminateThread syscall.
   7
   8 Differential Revision: https://reviews.llvm.org/D52091
   9
  10 ** Update for clang 9 ** : After some backouts, this patch eventually landed
  11 upstream in a different form, as the TLS handler `asan_thread_exit`, but that
  12 variant causes failures in our test suite, so revert the TLS handler in favor of
  13 the interceptor approach from the first patch.
  14
  15 diff --git a/compiler-rt/lib/asan/asan_win.cpp b/compiler-rt/lib/asan/asan_win.cpp
  16 index 417892aaedd..5fe86db44f4 100644
  17 --- a/compiler-rt/lib/asan/asan_win.cpp
  18 +++ b/compiler-rt/lib/asan/asan_win.cpp
  19 @@ -154,6 +154,14 @@ INTERCEPTOR_WINAPI(HANDLE, CreateThread, LPSECURITY_ATTRIBUTES security,
  20                              thr_flags, tid);
  21  }
  22
  23 +INTERCEPTOR_WINAPI(void, NtTerminateThread, void *rcx) {
  24 +  // Unpoison the terminating thread's stack because the memory may be re-used.
  25 +  NT_TIB *tib = (NT_TIB *)NtCurrentTeb();
  26 +  uptr stackSize = (uptr)tib->StackBase - (uptr)tib->StackLimit;
  27 +  __asan_unpoison_memory_region(tib->StackLimit, stackSize);
  28 +  return REAL(NtTerminateThread(rcx));
  29 +}
  30 +
  31  // }}}
  32
  33  namespace __asan {
  34 @@ -168,7 +176,9 @@ void InitializePlatformInterceptors() {
  35
  36    ASAN_INTERCEPT_FUNC(CreateThread);
  37    ASAN_INTERCEPT_FUNC(SetUnhandledExceptionFilter);
  38 -
  39 +  CHECK(::__interception::OverrideFunction("NtTerminateThread",
  40 +                                           (uptr)WRAP(NtTerminateThread),
  41 +                                           (uptr *)&REAL(NtTerminateThread)));
  42  #ifdef _WIN64
  43    ASAN_INTERCEPT_FUNC(__C_specific_handler);
  44  #else
  45 @@ -380,19 +390,6 @@ __declspec(allocate(".CRT$XLAB")) void(NTAPI *__asan_tls_init)(
  46      void *, unsigned long, void *) = asan_thread_init;
  47  #endif
  48
  49 -static void NTAPI asan_thread_exit(void *module, DWORD reason, void *reserved) {
  50 -  if (reason == DLL_THREAD_DETACH) {
  51 -    // Unpoison the thread's stack because the memory may be re-used.
  52 -    NT_TIB *tib = (NT_TIB *)NtCurrentTeb();
  53 -    uptr stackSize = (uptr)tib->StackBase - (uptr)tib->StackLimit;
  54 -    __asan_unpoison_memory_region(tib->StackLimit, stackSize);
  55 -  }
  56 -}
  57 -
  58 -#pragma section(".CRT$XLY", long, read)
  59 -__declspec(allocate(".CRT$XLY")) void(NTAPI *__asan_tls_exit)(
  60 -    void *, unsigned long, void *) = asan_thread_exit;
  61 -
  62  WIN_FORCE_LINK(__asan_dso_reg_hook)
  63
  64  // }}}