[PATCH] D58641: [winasan] Unpoison stack memory when threads exit (redux)

[David Major via Phabricator via llvm-commits]

dmajor created this revision.
dmajor added a reviewer: rnk.
Herald added subscribers: Sanitizers, llvm-commits, jdoerfert.
Herald added projects: LLVM, Sanitizers.

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.


Repository:
  rCRT Compiler Runtime

https://reviews.llvm.org/D58641

Files:
  asan_win.cc


Index: asan_win.cc
===================================================================
--- asan_win.cc
+++ asan_win.cc
@@ -354,6 +354,19 @@
     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$XLZ", long, read)  // NOLINT
+__declspec(allocate(".CRT$XLZ")) void (NTAPI *__asan_tls_exit)(void *,
+    unsigned long, void *) = asan_thread_exit;
+
 WIN_FORCE_LINK(__asan_dso_reg_hook)
 
 // }}}


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