netdev - [lvc-project] [PATCH] netfilter: nfnetlink: NULL-check skb->dev in __build_packet

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Date:   Mon, 27 Mar 2023 12:41:16 +0300
From:   Igor Artemiev <Igor.A.Artemiev@...t.ru>
To:     Pablo Neira Ayuso <pablo@...filter.org>
Cc:     Igor Artemiev <Igor.A.Artemiev@...t.ru>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [lvc-project] [PATCH] netfilter: nfnetlink: NULL-check skb->dev in __build_packet_message()

After having been compared to NULL value at nfnetlink_log.c:560,
pointer 'skb->dev' is dereferenced at nfnetlink_log.c:576.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Igor Artemiev <Igor.A.Artemiev@...t.ru>
---
 net/netfilter/nfnetlink_log.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index d97eb280cb2e..2711509eb9a5 100644
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -572,7 +572,7 @@ __build_packet_message(struct nfnl_log_net *log,
 		}
 	}
 
-	if (indev && skb_mac_header_was_set(skb)) {
+	if (indev && skb->dev && skb_mac_header_was_set(skb)) {
 		if (nla_put_be16(inst->skb, NFULA_HWTYPE, htons(skb->dev->type)) ||
 		    nla_put_be16(inst->skb, NFULA_HWLEN,
 				 htons(skb->dev->hard_header_len)))
-- 
2.30.2