From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Thu, 10 Jun 2021 18:20:31 +0000 (+0200)
Subject: netfilter: nft_osf: check for TCP packet before further processing
X-Git-Tag: v4.19.198~283
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3225cd78880a15928f8930e3de698a6edca63f42;p=thirdparty%2Fkernel%2Fstable.git

netfilter: nft_osf: check for TCP packet before further processing

[ 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>
---

diff --git a/net/netfilter/nft_osf.c b/net/netfilter/nft_osf.c
index a003533ff4d93..e259454b6a643 100644
--- a/net/netfilter/nft_osf.c
+++ b/net/netfilter/nft_osf.c
@@ -22,6 +22,11 @@ static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
 	struct tcphdr _tcph;
 	const char *os_name;
 
+	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) {