linux-kernel - [PATCH] net: ethernet: aeroflex: fix UAF in greth_of

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Date:   Fri, 18 Jun 2021 17:57:31 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     andreas@...sler.com, davem@...emloft.net, kuba@...nel.org,
        kristoffer@...sler.com
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        Pavel Skripkin <paskripkin@...il.com>
Subject: [PATCH] net: ethernet: aeroflex: fix UAF in greth_of_remove

static int greth_of_remove(struct platform_device *of_dev)
{
...
	struct greth_private *greth = netdev_priv(ndev);
...
	unregister_netdev(ndev);
	free_netdev(ndev);

	of_iounmap(&of_dev->resource[0], greth->regs, resource_size(&of_dev->resource[0]));
...
}

greth is netdev private data, but it is used
after free_netdev(). It can cause use-after-free when accessing greth
pointer. So, fix it by moving free_netdev() after of_iounmap()
call.

Fixes: d4c41139df6e ("net: Add Aeroflex Gaisler 10/100/1G Ethernet MAC driver")
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
---
 drivers/net/ethernet/aeroflex/greth.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/aeroflex/greth.c b/drivers/net/ethernet/aeroflex/greth.c
index d77fafbc1530..c560ad06f0be 100644
--- a/drivers/net/ethernet/aeroflex/greth.c
+++ b/drivers/net/ethernet/aeroflex/greth.c
@@ -1539,10 +1539,11 @@ static int greth_of_remove(struct platform_device *of_dev)
 	mdiobus_unregister(greth->mdio);
 
 	unregister_netdev(ndev);
-	free_netdev(ndev);
 
 	of_iounmap(&of_dev->resource[0], greth->regs, resource_size(&of_dev->resource[0]));
 
+	free_netdev(ndev);
+
 	return 0;
 }
 
-- 
2.32.0