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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Pablo Neira Ayuso <pablo@netfilter.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.12 420/700] netfilter: nft_exthdr: check for IPv6 packet before further processing
Date:   Mon, 12 Jul 2021 08:08:23 +0200
Message-Id: <20210712061021.078143307@linuxfoundation.org>
In-Reply-To: <20210712060924.797321836@linuxfoundation.org>
References: <20210712060924.797321836@linuxfoundation.org>
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From: Pablo Neira Ayuso <pablo@netfilter.org>

[ 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>
---
 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 f64f0017e9a5..670dd146fb2b 100644
--- 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);
-- 
2.30.2