Fix a small race condition in sip_tcp_locate().

We must increase the reference count on the tcptls_session _before_ unlocking
the thread list.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@163667 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -20326,22 +20326,28 @@ static int sip_standard_port(enum sip_transport type, int port)
 		return port == STANDARD_SIP_PORT;
 }
 
-/*! \todo Find thread for TCP/TLS session (based on IP/Port */
+/*! 
+ * \brief Find thread for TCP/TLS session (based on IP/Port 
+ *
+ * \note This function returns an astobj2 reference
+ */
 static struct ast_tcptls_session_instance *sip_tcp_locate(struct sockaddr_in *s)
 {
 	struct sip_threadinfo *th;
+	struct ast_tcptls_session_instance *tcptls_instance = NULL;
 
 	AST_LIST_LOCK(&threadl);
 	AST_LIST_TRAVERSE(&threadl, th, list) {
 		if ((s->sin_family == th->ser->remote_address.sin_family) &&
 			(s->sin_addr.s_addr == th->ser->remote_address.sin_addr.s_addr) &&
 			(s->sin_port == th->ser->remote_address.sin_port))  {
-				AST_LIST_UNLOCK(&threadl);
-				return th->ser;
+				tcptls_instance = (ao2_ref(th->ser, +1), th->ser);
+				break;
 			}
 	}
 	AST_LIST_UNLOCK(&threadl);
-	return NULL;
+
+	return tcptls_instance;
 }
 
 /*! \todo Get socket for dialog, prepare if needed, and return file handle  */
@@ -20378,7 +20384,6 @@ static int sip_prepare_socket(struct sip_pvt *p)
 			ao2_ref(s->ser, -1);
 			s->ser = NULL;
 		}
-		ao2_ref(ser, +1);
 		s->ser = ser;
 		return s->fd;
 	}