rxrpc: Check the source of a packet to a client conn

When looking up a client connection to which to route a packet, we need to
check that the packet came from the correct source so that a peer can't try
to muck around with another peer's connection.

Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/conn_object.c

@@ -508,7 +508,9 @@ struct rxrpc_connection *rxrpc_find_connection(struct rxrpc_local *local,
 		}
 	} else {
 		conn = idr_find(&rxrpc_client_conn_ids, cid >> RXRPC_CIDSHIFT);
-		if (conn && conn->proto.epoch == epoch)
+		if (conn &&
+		    conn->proto.epoch == epoch &&
+		    conn->params.peer == peer)
 			goto found;
 	}