avoid a double-free bug

* src/qemu_conf.c (qemudParseXML): Ensure that "obj" is either
NULL or a valid malloc'd pointer before we might "goto error"
where it is freed.

ChangeLog

+Fri May 16 11:29:30 CEST 2008 Jim Meyering <meyering@redhat.com>
+
+	avoid a double-free bug
+	* src/qemu_conf.c (qemudParseXML): Ensure that "obj" is either
+	NULL or a valid malloc'd pointer before we might "goto error"
+	where it is freed.
+
 Thu May 15 16:06:08 EST 2008 Daniel P. Berrange <berrange@redhat.com>
 
 	* src/qemu_conf.c: Remove use of strcmp()

src/qemu_conf.c

@@ -1736,6 +1736,7 @@ static struct qemud_vm_def *qemudParseXML(virConnectPtr conn,
     } else {
         strcpy(def->os.type, (const char *)obj->stringval);
         xmlXPathFreeObject(obj);
+        obj = NULL;
     }
 
     if (!virCapabilitiesSupportsGuestOSType(driver->caps, def->os.type)) {