[winasan] Unpoison stack memory when threads exit (redux)

This is a second attempt at r342652 using a TLS callback instead of an
interceptor.

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 callback that unpoisons the
stack memory when a thread exits.

Differential Revision: https://reviews.llvm.org/D58641

llvm-svn: 354836

1 files changed, 13 insertions, 0 deletions

diff --git a/compiler-rt/lib/asan/asan_win.cc b/compiler-rt/lib/asan/asan_win.cc
index 692da58234a..3eee845ee41 100644
--- a/compiler-rt/lib/asan/asan_win.cc
+++ b/compiler-rt/lib/asan/asan_win.cc
@@ -354,6 +354,19 @@ __declspec(allocate(".CRT$XLAB")) void (NTAPI *__asan_tls_init)(void *,
     unsigned long, void *) = asan_thread_init;
 #endif
 
+static void NTAPI asan_thread_exit(void *module, DWORD reason, void *reserved) {
+  if (reason == DLL_THREAD_DETACH) {
+    // Unpoison the thread's stack because the memory may be re-used.
+    NT_TIB *tib = (NT_TIB *)NtCurrentTeb();
+    uptr stackSize = (uptr)tib->StackBase - (uptr)tib->StackLimit;
+    __asan_unpoison_memory_region(tib->StackLimit, stackSize);
+  }
+}
+
+#pragma section(".CRT$XLY", long, read)  // NOLINT
+__declspec(allocate(".CRT$XLY")) void (NTAPI *__asan_tls_exit)(void *,
+    unsigned long, void *) = asan_thread_exit;
+
 WIN_FORCE_LINK(__asan_dso_reg_hook)
 
 // }}}