netdev - [PATCH net] net: phy: marvell10g: fix null pointer dereference

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Date:   Mon, 10 Aug 2020 17:01:58 +0200
From:   Marek Behún <marek.behun@....cz>
To:     netdev@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Marek Behún <marek.behun@....cz>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>,
        Andrew Lunn <andrew@...n.ch>, Baruch Siach <baruch@...s.co.il>,
        Russell King <rmk+kernel@...linux.org.uk>
Subject: [PATCH net] net: phy: marvell10g: fix null pointer dereference

Commit c3e302edca24 ("net: phy: marvell10g: fix temperature sensor on 2110")
added a check for PHY ID via phydev->drv->phy_id in a function which is
called by devres at a time when phydev->drv is already set to null by
phy_remove function.

This null pointer dereference can be triggered via SFP subsystem with a
SFP module containing this Marvell PHY. When the SFP interface is put
down, the SFP subsystem removes the PHY.

Fixes: c3e302edca24 ("net: phy: marvell10g: fix temperature sensor on 2110")
Signed-off-by: Marek Behún <marek.behun@....cz>
Cc: Maxime Chevallier <maxime.chevallier@...tlin.com>
Cc: Andrew Lunn <andrew@...n.ch>
Cc: Baruch Siach <baruch@...s.co.il>
Cc: Russell King <rmk+kernel@...linux.org.uk>
---
 drivers/net/phy/marvell10g.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/net/phy/marvell10g.c b/drivers/net/phy/marvell10g.c
index a7610eb55f30f..1901ba277413d 100644
--- a/drivers/net/phy/marvell10g.c
+++ b/drivers/net/phy/marvell10g.c
@@ -208,13 +208,6 @@ static int mv3310_hwmon_config(struct phy_device *phydev, bool enable)
 			      MV_V2_TEMP_CTRL_MASK, val);
 }
 
-static void mv3310_hwmon_disable(void *data)
-{
-	struct phy_device *phydev = data;
-
-	mv3310_hwmon_config(phydev, false);
-}
-
 static int mv3310_hwmon_probe(struct phy_device *phydev)
 {
 	struct device *dev = &phydev->mdio.dev;
@@ -238,10 +231,6 @@ static int mv3310_hwmon_probe(struct phy_device *phydev)
 	if (ret)
 		return ret;
 
-	ret = devm_add_action_or_reset(dev, mv3310_hwmon_disable, phydev);
-	if (ret)
-		return ret;
-
 	priv->hwmon_dev = devm_hwmon_device_register_with_info(dev,
 				priv->hwmon_name, phydev,
 				&mv3310_hwmon_chip_info, NULL);
@@ -426,6 +415,11 @@ static int mv3310_probe(struct phy_device *phydev)
 	return phy_sfp_probe(phydev, &mv3310_sfp_ops);
 }
 
+static void mv3310_remove(struct phy_device *phydev)
+{
+	mv3310_hwmon_config(phydev, false);
+}
+
 static int mv3310_suspend(struct phy_device *phydev)
 {
 	return mv3310_power_down(phydev);
@@ -784,6 +778,7 @@ static struct phy_driver mv3310_drivers[] = {
 		.read_status	= mv3310_read_status,
 		.get_tunable	= mv3310_get_tunable,
 		.set_tunable	= mv3310_set_tunable,
+		.remove		= mv3310_remove,
 	},
 	{
 		.phy_id		= MARVELL_PHY_ID_88E2110,
@@ -798,6 +793,7 @@ static struct phy_driver mv3310_drivers[] = {
 		.read_status	= mv3310_read_status,
 		.get_tunable	= mv3310_get_tunable,
 		.set_tunable	= mv3310_set_tunable,
+		.remove		= mv3310_remove,
 	},
 };
 
-- 
2.26.2