netfilter: nft_socket: Break evaluation if no socket found

Actual implementation stores 0 in the destination register if no socket
is found by the lookup, but that is not intentional as it is not really
a value of any socket metadata.

This patch fixes this and breaks rule evaluation in this case.

Fixes: 554ced0a6e29 ("netfilter: nf_tables: add support for native socket matching")
Signed-off-by: Máté Eckl <ecklm94@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_socket.c

@@ -43,7 +43,7 @@ static void nft_socket_eval(const struct nft_expr *expr,
 		}
 
 	if (!sk) {
-		nft_reg_store8(dest, 0);
+		regs->verdict.code = NFT_BREAK;
 		return;
 	}