[winasan] Unpoison the stack in NtTerminateThread

[dmajor]

Summary

In long-running builds we've seen some ASan complaints during thread creation that we suspect are due to leftover poisoning from previous threads whose stacks occupied that memory. This patch adds a hook that unpoisons the stack just before the NtTerminateThread syscall.

[rnk]

lgtm

[hans]

This appears to have caused the thread exit code to get clobbered, as shown by some Chromium test failures: https://bugs.chromium.org/p/chromium/issues/detail?id=890310

I've reverted in r343322.

[rnk]

I think NtTerminateThread has a richer prototype:
NTEXPORT NTSTATUS NTAPI
NtTerminateThread(IN HANDLE ThreadHandle OPTIONAL, IN NTSTATUS ExitStatus)
https://github.com/DynamoRIO/dynamorio/blob/f1713ec4a9a856d1038c6095da67a5bd95b6a1c7/core/win32/ntdll_imports.c#L154
http://codewarrior.cn/ntdoc/win2k/ps/NtTerminateThread.htm

It should be fine to recommit with a better prototype.

[dmajor]

Relanded in r343606.

lib/asan/asan_win.cc

INTERCEPTOR_WINAPI(DWORD, CreateThread,
   bool detached = false;  // FIXME: how can we determine it on Windows?
   u32 current_tid = GetCurrentTidOrInvalid();
   AsanThread *t =
         AsanThread::Create(start_routine, arg, current_tid, &stack, detached);
   return REAL(CreateThread)(security, stack_size,
                             asan_thread_start, t, thr_flags, tid);
 }
 
+INTERCEPTOR_WINAPI(void, NtTerminateThread, void* rcx) {
+  // Unpoison the terminating thread's stack because the memory may be re-used.
+  NT_TIB* pTib = reinterpret_cast<NT_TIB*>(NtCurrentTeb());
+  uptr stackSize = (uptr)pTib->StackBase - (uptr)pTib->StackLimit;
+  __asan_unpoison_memory_region(pTib->StackLimit, stackSize);
+  return REAL(NtTerminateThread(rcx));
+}
+
 // }}}
 
 namespace __asan {
 
 void InitializePlatformInterceptors() {
   ASAN_INTERCEPT_FUNC(CreateThread);
   ASAN_INTERCEPT_FUNC(SetUnhandledExceptionFilter);
-
+  CHECK(::__interception::OverrideFunction("NtTerminateThread",             
+                                           (uptr)WRAP(NtTerminateThread),
+                                           (uptr *)&REAL(NtTerminateThread)));
 #ifdef _WIN64
   ASAN_INTERCEPT_FUNC(__C_specific_handler);
 #else
   ASAN_INTERCEPT_FUNC(_except_handler3);
   ASAN_INTERCEPT_FUNC(_except_handler4);
 #endif
 
   // Try to intercept kernel32!RaiseException, and if that fails, intercept