linux-kernel - [PATCH net v2 3/3] ethernet: ucc_geth: fix use-after-free in ucc_geth

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Date:   Fri, 18 Dec 2020 11:55:38 +0100
From:   Rasmus Villemoes <rasmus.villemoes@...vas.dk>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, Zhao Qiang <qiang.zhao@....com>,
        Li Yang <leoyang.li@....com>, Andrew Lunn <andrew@...n.ch>,
        linux-kernel@...r.kernel.org,
        Rasmus Villemoes <rasmus.villemoes@...vas.dk>
Subject: [PATCH net v2 3/3] ethernet: ucc_geth: fix use-after-free in ucc_geth_remove()

ugeth is the netdiv_priv() part of the netdevice. Accessing the memory
pointed to by ugeth (such as done by ucc_geth_memclean() and the two
of_node_puts) after free_netdev() is thus use-after-free.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@...vas.dk>
---
 drivers/net/ethernet/freescale/ucc_geth.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/ucc_geth.c b/drivers/net/ethernet/freescale/ucc_geth.c
index 380c1f09adaf..3f9fca061cc0 100644
--- a/drivers/net/ethernet/freescale/ucc_geth.c
+++ b/drivers/net/ethernet/freescale/ucc_geth.c
@@ -3935,12 +3935,12 @@ static int ucc_geth_remove(struct platform_device* ofdev)
 	struct device_node *np = ofdev->dev.of_node;
 
 	unregister_netdev(dev);
-	free_netdev(dev);
 	ucc_geth_memclean(ugeth);
 	if (of_phy_is_fixed_link(np))
 		of_phy_deregister_fixed_link(np);
 	of_node_put(ugeth->ug_info->tbi_node);
 	of_node_put(ugeth->ug_info->phy_node);
+	free_netdev(dev);
 
 	return 0;
 }
-- 
2.23.0