[PATCH 4.19 137/421] netfilter: nft_exthdr: check for IPv6 packet before further processing

[Greg Kroah-Hartman]

From: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/netfilter/nft_exthdr.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index a940c9fd9045..64e69d6683ca 100644
--- 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);
-- 
2.30.2