[patch] patch to a potential segfault due to weak symbols on pthreads

libxml2-2.7.7-fix-weak-symbols.patch (text/plain), 1.99 KB, created by Christoph Junghans (RETIRED) on 2010-10-16 16:40:05 UTC

From e6f05099e8de3c89201aa92c5d6f0286b9299522 Mon Sep 17 00:00:00 2001
From: Mike Hommey <[e-mail]>
Date: Fri, 15 Oct 2010 17:50:03 +0000
Subject: Fix a potential segfault due to weak symbols on pthreads

In xmlInitParser, both __xmlGlobalInitMutexLock and xmlInitGlobals are
called before xmlInitThreads, and both use pthread symbols.
__xmlGlobalInitMutexLock does so directly, without checking if the symbol
exists, and xmlInitGlobals calls xmlNewMutex, which correctly depends on
libxml_is_threaded... except libxml_is_threaded is still -1 by then...
And again, when releasing the global mutex in __xmlGlobalInitMutexUnlock,
the pthread function is called directly.

The patch changes the initialization order and make sure the functions
are available before calling them
---
diff --git a/parser.c b/parser.c
index 85e7599..1db706b 100644
--- a/parser.c
+++ b/parser.c
@@ -14004,8 +14004,8 @@ xmlInitParser(void) {
     __xmlGlobalInitMutexLock();
     if (xmlParserInitialized == 0) {
 #endif
-	xmlInitGlobals();
 	xmlInitThreads();
+	xmlInitGlobals();
 	if ((xmlGenericError == xmlGenericErrorDefaultFunc) ||
 	    (xmlGenericError == NULL))
 	    initGenericErrorDefaultFunc(NULL);
diff --git a/threads.c b/threads.c
index 98fd2c2..1eeac0e 100644
--- a/threads.c
+++ b/threads.c
@@ -439,7 +439,8 @@ __xmlGlobalInitMutexLock(void)
     /* Make sure the global init lock is initialized and then lock it. */
 #ifdef HAVE_PTHREAD_H
     /* The mutex is statically initialized, so we just lock it. */
-    pthread_mutex_lock(&global_init_lock);
+    if (pthread_mutex_lock)
+        pthread_mutex_lock(&global_init_lock);
 #elif defined HAVE_WIN32_THREADS
     LPCRITICAL_SECTION cs;
 
@@ -508,7 +509,8 @@ void
 __xmlGlobalInitMutexUnlock(void)
 {
 #ifdef HAVE_PTHREAD_H
-    pthread_mutex_unlock(&global_init_lock);
+    if (pthread_mutex_unlock)
+        pthread_mutex_unlock(&global_init_lock);
 #elif defined HAVE_WIN32_THREADS
     if (global_init_lock != NULL) {
 	LeaveCriticalSection(global_init_lock);
--
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