From e0aba54bd1935ab7f33969359651e615e363c14c Mon Sep 17 00:00:00 2001
From: Matthias Bolte <matthias.bolte@googlemail.com>
Date: Sat, 21 Apr 2012 19:03:08 +0200
Subject: [PATCH] win32: Properly handle TlsGetValue returning NULL
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virThreadSelf tries to access the virThreadPtr stored in TLS for the
current thread via TlsGetValue. When virThreadSelf is called on a thread
that was not created via virThreadCreate (e.g. the main thread) then
TlsGetValue returns NULL as TlsAlloc initializes TLS slots to NULL.

virThreadSelf can be called on the main thread via this call chain from
virsh

vshDeinit
virEventAddTimeout
virEventPollAddTimeout
virEventPollInterruptLocked
virThreadIsSelf

triggering a segfault as virThreadSelf unconditionally dereferences the
return value of TlsGetValue.

Fix this by making virThreadSelf check the TLS slot value for NULL and
setting the given virThreadPtr accordingly.

Reported by Marcel Müller.
---
 src/util/threads-win32.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/util/threads-win32.c b/src/util/threads-win32.c
index 157439ceae..20756a107f 100644
--- a/src/util/threads-win32.c
+++ b/src/util/threads-win32.c
@@ -316,8 +316,15 @@ int virThreadCreate(virThreadPtr thread,
 void virThreadSelf(virThreadPtr thread)
 {
     virThreadPtr self = TlsGetValue(selfkey);
-    thread->thread = self->thread;
-    thread->joinable = self->joinable;
+
+    if (self == NULL) {
+        /* called on a thread not created by virThreadCreate, e.g. the main thread */
+        thread->thread = 0;
+        thread->joinable = false;
+    } else {
+        thread->thread = self->thread;
+        thread->joinable = self->joinable;
+    }
 }
 
 bool virThreadIsSelf(virThreadPtr thread)