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From:   Yuri Karpov <YKarpov@ispras.ru>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Yuri Karpov <YKarpov@ispras.ru>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org
Subject: [PATCH] net: dsa: fix NULL pointer dereference in seq_match()
Date:   Wed, 30 Nov 2022 11:44:31 +0300
Message-Id: <20221130084431.3299054-1-YKarpov@ispras.ru>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

ptp_parse_header() result is not checked in seq_match() that can lead
to NULL pointer dereferense.

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

Fixes: c6fe0ad2c349 ("net: dsa: mv88e6xxx: add rx/tx timestamping support")
Signed-off-by: Yuri Karpov <YKarpov@ispras.ru>
---
 drivers/net/dsa/mv88e6xxx/hwtstamp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/dsa/mv88e6xxx/hwtstamp.c b/drivers/net/dsa/mv88e6xxx/hwtstamp.c
index 331b4ca089ff..97f30795a2bb 100644
--- a/drivers/net/dsa/mv88e6xxx/hwtstamp.c
+++ b/drivers/net/dsa/mv88e6xxx/hwtstamp.c
@@ -246,7 +246,7 @@ static int seq_match(struct sk_buff *skb, u16 ts_seqid)
 
 	hdr = ptp_parse_header(skb, type);
 
-	return ts_seqid == ntohs(hdr->sequence_id);
+	return hdr ? ts_seqid == ntohs(hdr->sequence_id) : 0;
 }
 
 static void mv88e6xxx_get_rxts(struct mv88e6xxx_chip *chip,
-- 
2.34.1