netfilter: nft_exthdr: check for IPv6 packet before further processing

[ Upstream commit cdd73cc545c0fb9b1a1f7b209f4f536e7990cff4 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index a940c9fd9045e5495a42d93f76db26283c6de5f1..64e69d6683cab4967dccb8b20dfda6d095691a19 100644 (file)
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -45,6 +45,9 @@ 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) {
                *dest = (err >= 0);