net: pasemi: fix an use-after-free in pasemi_mac_phy_init()

BugLink: https://bugs.launchpad.net/bugs/1864773

[ Upstream commit faf5577f ]

The phy_dn variable is still being used in of_phy_connect() after the
of_node_put() call, which may result in use-after-free.

Fixes: 1dd2d06c ("net: Rework pasemi_mac driver to use of_mdio infrastructure")
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/net/ethernet/pasemi/pasemi_mac.c

@@ -1091,7 +1091,6 @@ static int pasemi_mac_phy_init(struct net_device *dev)
 
 	dn = pci_device_to_OF_node(mac->pdev);
 	phy_dn = of_parse_phandle(dn, "phy-handle", 0);
-	of_node_put(phy_dn);
 
 	mac->link = 0;
 	mac->speed = 0;
@@ -1100,6 +1099,7 @@ static int pasemi_mac_phy_init(struct net_device *dev)
 	phydev = of_phy_connect(dev, phy_dn, &pasemi_adjust_link, 0,
 				PHY_INTERFACE_MODE_SGMII);
 
+	of_node_put(phy_dn);
 	if (!phydev) {
 		printk(KERN_ERR "%s: Could not attach to phy\n", dev->name);
 		return -ENODEV;