Save the callno when we're poking, because our peer structure could change

during destruction (and thus we unlock the wrong callno, causing a
cascade failure).
(closes issue #12717)
 Reported by: gewfie
 Patches: 
       20080525__bug12717.diff.txt uploaded by Corydon76 (license 14)
 Tested by: gewfie


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@120001 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_iax2.c

@@ -8842,6 +8842,7 @@ static int iax2_poke_peer_cb(void *obj, void *arg, int flags)
 
 static int iax2_poke_peer(struct iax2_peer *peer, int heldcall)
 {
+	int callno;
 	if (!peer->maxms || (!peer->addr.sin_addr.s_addr && !peer->dnsmgr)) {
 		/* IF we have no IP without dnsmgr, or this isn't to be monitored, return
 		  immediately after clearing things out */
@@ -8851,11 +8852,13 @@ static int iax2_poke_peer(struct iax2_peer *peer, int heldcall)
 		peer->callno = 0;
 		return 0;
 	}
-	if (peer->callno > 0) {
+
+	/* The peer could change the callno inside iax2_destroy, since we do deadlock avoidance */
+	if ((callno = peer->callno) > 0) {
 		ast_log(LOG_NOTICE, "Still have a callno...\n");
-		ast_mutex_lock(&iaxsl[peer->callno]);
-		iax2_destroy(peer->callno);
-		ast_mutex_unlock(&iaxsl[peer->callno]);
+		ast_mutex_lock(&iaxsl[callno]);
+		iax2_destroy(callno);
+		ast_mutex_unlock(&iaxsl[callno]);
 	}
 	if (heldcall)
 		ast_mutex_unlock(&iaxsl[heldcall]);