netfilter: nft_exthdr: check for IPv6 packet before further processing

ipv6_find_hdr() does not validate that this is an IPv6 packet. Add a
sanity check for calling ipv6_find_hdr() to make sure an IPv6 packet
is passed for parsing.

Fixes: 96518518cc41 ("netfilter: add nftables")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index f64f0017e9a530bca0e4f100e2f6a6f27349074c..670dd146fb2b16be550ae2874aadb9cb4979f0bf 100644 (file)
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -42,6 +42,9 @@ static void nft_exthdr_ipv6_eval(const struct nft_expr *expr,
        unsigned int offset = 0;
        int err;
 
+       if (pkt->skb->protocol != htons(ETH_P_IPV6))
+               goto err;
+
        err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL);
        if (priv->flags & NFT_EXTHDR_F_PRESENT) {
                nft_reg_store8(dest, err >= 0);