net: phy: marvell10g: fix null pointer dereference

Commit c3e302ed ("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: c3e302ed ("net: phy: marvell10g: fix temperature sensor on 2110")
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Cc: Maxime Chevallier <maxime.chevallier@bootlin.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Baruch Siach <baruch@tkos.co.il>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

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,
 	},
 };