linux-kernel - [PATCH] net: dsa: avoid null pointer dereference on p->phy

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Message-Id: <20170923165720.18560-1-colin.king@canonical.com>
Date:   Sat, 23 Sep 2017 17:57:20 +0100
From:   Colin King <colin.king@...onical.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...oirfairelinux.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] net: dsa: avoid null pointer dereference on p->phy

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

Currently p->phy is being null checked in several places to avoid
null pointer dereferences on p->phy, however, the final call
to phy_attached_info on p->phy when p->phy will perform a null
pointer dereference. Fix this by simply moving the call into
the previous code block that is only executed if p->phy is
not null.

Detected by CoverityScan, CID#1457034 ("Dereference after null check")

Fixes: 2220943a21e2 ("phy: Centralise print about attached phy")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 net/dsa/slave.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 02ace7d462c4..29ab4e98639b 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -1115,10 +1115,9 @@ static int dsa_slave_phy_setup(struct net_device *slave_dev)
 				of_phy_deregister_fixed_link(port_dn);
 			return ret;
 		}
+		phy_attached_info(p->phy);
 	}
 
-	phy_attached_info(p->phy);
-
 	return 0;
 }
 
-- 
2.14.1