net/rxrpc/ar-connection.c: fix NULL dereference

@@ -200,29 +200,29 @@ static struct rxrpc_connection *rxrpc_al
 	if (conn) {
 		INIT_WORK(&conn->processor, &rxrpc_process_connection);
 		INIT_LIST_HEAD(&conn->bundle_link);
 		conn->calls = RB_ROOT;
 		skb_queue_head_init(&conn->rx_queue);
 		rwlock_init(&conn->lock);
 		spin_lock_init(&conn->state_lock);
 		atomic_set(&conn->usage, 1);
 		conn->debug_id = atomic_inc_return(&rxrpc_debug_id);
 		conn->avail_calls = RXRPC_MAXCALLS;
 		conn->size_align = 4;
 		conn->header_size = sizeof(struct rxrpc_header);
 	}
 
-	_leave(" = %p{%d}", conn, conn->debug_id);
+	_leave(" = %p{%d}", conn, conn ? conn->debug_id : 0);
 	return conn;
 }
 
 /*
  * assign a connection ID to a connection and add it to the transport's
  * connection lookup tree
  * - called with transport client lock held
  */
 static void rxrpc_assign_connection_id(struct rxrpc_connection *conn)
 {
 	struct rxrpc_connection *xconn;
 	struct rb_node *parent, **p;
 	__be32 epoch;
 	u32 real_conn_id;