linux-kernel - [PATCH] net: dsa: b53: Fix dereference of null dev

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Message-Id: <20210612144407.60259-1-colin.king@canonical.com>
Date:   Sat, 12 Jun 2021 15:44:07 +0100
From:   Colin King <colin.king@...onical.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] net: dsa: b53: Fix dereference of null dev

From: Colin Ian King <colin.king@...onical.com>

Currently pointer priv is dereferencing dev before dev is being null
checked so a potential null pointer dereference can occur. Fix this
by only assigning and using priv if dev is not-null.

Addresses-Coverity: ("Dereference before null check")
Fixes: 16994374a6fc ("net: dsa: b53: Make SRAB driver manage port interrupts")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/net/dsa/b53/b53_srab.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/dsa/b53/b53_srab.c b/drivers/net/dsa/b53/b53_srab.c
index aaa12d73784e..e77ac598f859 100644
--- a/drivers/net/dsa/b53/b53_srab.c
+++ b/drivers/net/dsa/b53/b53_srab.c
@@ -629,11 +629,13 @@ static int b53_srab_probe(struct platform_device *pdev)
 static int b53_srab_remove(struct platform_device *pdev)
 {
 	struct b53_device *dev = platform_get_drvdata(pdev);
-	struct b53_srab_priv *priv = dev->priv;
 
-	b53_srab_intr_set(priv, false);
-	if (dev)
+	if (dev) {
+		struct b53_srab_priv *priv = dev->priv;
+
+		b53_srab_intr_set(priv, false);
 		b53_switch_remove(dev);
+	}
 
 	return 0;
 }
-- 
2.31.1