net: phy: dp83822: Fix NULL pointer dereference on DP83825 devices

The probe() function is only used for DP83822 and DP83826 PHY,
leaving the private data pointer uninitialized for the DP83825 models
which causes a NULL pointer dereference in the recently introduced/changed
functions dp8382x_config_init() and dp83822_set_wol().

Add the dp8382x_probe() function, so all PHY models will have a valid
private data pointer to fix this issue and also prevent similar issues
in the future.

Fixes: 9ef9ecf ("net: phy: dp8382x: keep WOL settings across suspends")
Signed-off-by: Tomas Paukrt <tomaspaukrt@email.cz>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/66w.ZbGt.65Ljx42yHo5.1csjxu@seznam.cz
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: tpaukrt

drivers/net/phy/dp83822.c

@@ -271,8 +271,7 @@ static int dp83822_config_intr(struct phy_device *phydev)
 				DP83822_ENERGY_DET_INT_EN |
 				DP83822_LINK_QUAL_INT_EN);
 
-		/* Private data pointer is NULL on DP83825 */
-		if (!dp83822 || !dp83822->fx_enabled)
+		if (!dp83822->fx_enabled)
 			misr_status |= DP83822_ANEG_COMPLETE_INT_EN |
 				       DP83822_DUP_MODE_CHANGE_INT_EN |
 				       DP83822_SPEED_CHANGED_INT_EN;
@@ -292,8 +291,7 @@ static int dp83822_config_intr(struct phy_device *phydev)
 				DP83822_PAGE_RX_INT_EN |
 				DP83822_EEE_ERROR_CHANGE_INT_EN);
 
-		/* Private data pointer is NULL on DP83825 */
-		if (!dp83822 || !dp83822->fx_enabled)
+		if (!dp83822->fx_enabled)
 			misr_status |= DP83822_ANEG_ERR_INT_EN |
 				       DP83822_WOL_PKT_INT_EN;
 
@@ -691,10 +689,9 @@ static int dp83822_read_straps(struct phy_device *phydev)
 	return 0;
 }
 
-static int dp83822_probe(struct phy_device *phydev)
+static int dp8382x_probe(struct phy_device *phydev)
 {
 	struct dp83822_private *dp83822;
-	int ret;
 
 	dp83822 = devm_kzalloc(&phydev->mdio.dev, sizeof(*dp83822),
 			       GFP_KERNEL);
@@ -703,6 +700,20 @@ static int dp83822_probe(struct phy_device *phydev)
 
 	phydev->priv = dp83822;
 
+	return 0;
+}
+
+static int dp83822_probe(struct phy_device *phydev)
+{
+	struct dp83822_private *dp83822;
+	int ret;
+
+	ret = dp8382x_probe(phydev);
+	if (ret)
+		return ret;
+
+	dp83822 = phydev->priv;
+
 	ret = dp83822_read_straps(phydev);
 	if (ret)
 		return ret;
@@ -717,14 +728,11 @@ static int dp83822_probe(struct phy_device *phydev)
 
 static int dp83826_probe(struct phy_device *phydev)
 {
-	struct dp83822_private *dp83822;
-
-	dp83822 = devm_kzalloc(&phydev->mdio.dev, sizeof(*dp83822),
-			       GFP_KERNEL);
-	if (!dp83822)
-		return -ENOMEM;
+	int ret;
 
-	phydev->priv = dp83822;
+	ret = dp8382x_probe(phydev);
+	if (ret)
+		return ret;
 
 	dp83826_of_init(phydev);
 
@@ -795,6 +803,7 @@ static int dp83822_resume(struct phy_device *phydev)
 		PHY_ID_MATCH_MODEL(_id),			\
 		.name		= (_name),			\
 		/* PHY_BASIC_FEATURES */			\
+		.probe          = dp8382x_probe,		\
 		.soft_reset	= dp83822_phy_reset,		\
 		.config_init	= dp8382x_config_init,		\
 		.get_wol = dp83822_get_wol,			\