netdev - [PATCH net] net: ftgmac100: fix potential NULL pointer access in ftgmac100_phy

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Message-ID: <2b80a77a-06db-4dd7-85dc-3a8e0de55a1d@gmail.com>
Date: Wed, 30 Jul 2025 22:23:23 +0200
From: Heiner Kallweit <hkallweit1@...il.com>
To: Andrew Lunn <andrew+netdev@...n.ch>, Simon Horman <horms@...nel.org>,
 Jakub Kicinski <kuba@...nel.org>, David Miller <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>
Cc: Jacky Chou <jacky_chou@...eedtech.com>,
 Jacob Keller <jacob.e.keller@...el.com>,
 "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH net] net: ftgmac100: fix potential NULL pointer access in
 ftgmac100_phy_disconnect

After the call to phy_disconnect() netdev->phydev is reset to NULL.
So fixed_phy_unregister() would be called with a NULL pointer as argument.
Therefore cache the phy_device before this call.

Fixes: e24a6c874601 ("net: ftgmac100: Get link speed and duplex for NC-SI")
Cc: stable@...r.kernel.org
Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/ethernet/faraday/ftgmac100.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
index 5d0c09068..a863f7841 100644
--- a/drivers/net/ethernet/faraday/ftgmac100.c
+++ b/drivers/net/ethernet/faraday/ftgmac100.c
@@ -1750,16 +1750,17 @@ static int ftgmac100_setup_mdio(struct net_device *netdev)
 static void ftgmac100_phy_disconnect(struct net_device *netdev)
 {
 	struct ftgmac100 *priv = netdev_priv(netdev);
+	struct phy_device *phydev = netdev->phydev;
 
-	if (!netdev->phydev)
+	if (!phydev)
 		return;
 
-	phy_disconnect(netdev->phydev);
+	phy_disconnect(phydev);
 	if (of_phy_is_fixed_link(priv->dev->of_node))
 		of_phy_deregister_fixed_link(priv->dev->of_node);
 
 	if (priv->use_ncsi)
-		fixed_phy_unregister(netdev->phydev);
+		fixed_phy_unregister(phydev);
 }
 
 static void ftgmac100_destroy_mdio(struct net_device *netdev)
-- 
2.50.1