netdev - [PATCH net-next 1/2] net: mdio: of: fix potential NULL pointer derefernce

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Message-Id: <20200130174451.17951-1-michael@walle.cc>
Date:   Thu, 30 Jan 2020 18:44:50 +0100
From:   Michael Walle <michael@...le.cc>
To:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Cc:     Richard Cochran <richardcochran@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>, Michael Walle <michael@...le.cc>
Subject: [PATCH net-next 1/2] net: mdio: of: fix potential NULL pointer derefernce

of_find_mii_timestamper() returns NULL if no timestamper is found.
Therefore, guard the unregister_mii_timestamper() calls.

Fixes: 1dca22b18421 ("net: mdio: of: Register discovered MII time stampers.")
Signed-off-by: Michael Walle <michael@...le.cc>
---
 drivers/of/of_mdio.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
index f5c2a5487761..db0ed5879803 100644
--- a/drivers/of/of_mdio.c
+++ b/drivers/of/of_mdio.c
@@ -81,13 +81,15 @@ static int of_mdiobus_register_phy(struct mii_bus *mdio,
 	else
 		phy = get_phy_device(mdio, addr, is_c45);
 	if (IS_ERR(phy)) {
-		unregister_mii_timestamper(mii_ts);
+		if (mii_ts)
+			unregister_mii_timestamper(mii_ts);
 		return PTR_ERR(phy);
 	}
 
 	rc = of_irq_get(child, 0);
 	if (rc == -EPROBE_DEFER) {
-		unregister_mii_timestamper(mii_ts);
+		if (mii_ts)
+			unregister_mii_timestamper(mii_ts);
 		phy_device_free(phy);
 		return rc;
 	}
@@ -116,7 +118,8 @@ static int of_mdiobus_register_phy(struct mii_bus *mdio,
 	 * register it */
 	rc = phy_device_register(phy);
 	if (rc) {
-		unregister_mii_timestamper(mii_ts);
+		if (mii_ts)
+			unregister_mii_timestamper(mii_ts);
 		phy_device_free(phy);
 		of_node_put(child);
 		return rc;
-- 
2.20.1