netfilter: nf_tables: fix wrong length for jump/goto verdicts

NFT_JUMP/GOTO erronously sets length to sizeof(void *).

We then allocate insufficient memory when such element is added to a vmap.
Suggested-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -4340,7 +4340,6 @@ static int nft_verdict_init(const struct nft_ctx *ctx, struct nft_data *data,
 	case NFT_CONTINUE:
 	case NFT_BREAK:
 	case NFT_RETURN:
-		desc->len = sizeof(data->verdict);
 		break;
 	case NFT_JUMP:
 	case NFT_GOTO:
@@ -4355,10 +4354,10 @@ static int nft_verdict_init(const struct nft_ctx *ctx, struct nft_data *data,
 
 		chain->use++;
 		data->verdict.chain = chain;
-		desc->len = sizeof(data);
 		break;
 	}
 
+	desc->len = sizeof(data->verdict);
 	desc->type = NFT_DATA_VERDICT;
 	return 0;
 }