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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>,
        kernel test robot <lkp@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 213/348] netfilter: nft_osf: check for TCP packet before further processing
Date:   Mon, 12 Jul 2021 08:09:57 +0200
Message-Id: <20210712060729.822166307@linuxfoundation.org>
In-Reply-To: <20210712060659.886176320@linuxfoundation.org>
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From: Pablo Neira Ayuso <pablo@netfilter.org>

[ Upstream commit 8f518d43f89ae00b9cf5460e10b91694944ca1a8 ]

The osf expression only supports for TCP packets, add a upfront sanity
check to skip packet parsing if this is not a TCP packet.

Fixes: b96af92d6eaf ("netfilter: nf_tables: implement Passive OS fingerprint module in nft_osf")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/netfilter/nft_osf.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/netfilter/nft_osf.c b/net/netfilter/nft_osf.c
index b42247aa48a9..4911f8eb394f 100644
--- a/net/netfilter/nft_osf.c
+++ b/net/netfilter/nft_osf.c
@@ -28,6 +28,11 @@ static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
 	struct nf_osf_data data;
 	struct tcphdr _tcph;
 
+	if (pkt->tprot != IPPROTO_TCP) {
+		regs->verdict.code = NFT_BREAK;
+		return;
+	}
+
 	tcp = skb_header_pointer(skb, ip_hdrlen(skb),
 				 sizeof(struct tcphdr), &_tcph);
 	if (!tcp) {
-- 
2.30.2