netdev - [PATCH 1/2] net: fec: fix use-after-free in fec_drv

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Message-Id: <25ad9ae695546c0ce23edb25cb2a67575cbda26b.1628091954.git.paskripkin@gmail.com>
Date:   Wed,  4 Aug 2021 18:51:51 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     davem@...emloft.net, kuba@...nel.org, qiangqing.zhang@....com,
        hslester96@...il.com, fugang.duan@....com
Cc:     dan.carpenter@...cle.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Pavel Skripkin <paskripkin@...il.com>
Subject: [PATCH 1/2] net: fec: fix use-after-free in fec_drv_remove

Smatch says:
	drivers/net/ethernet/freescale/fec_main.c:3994 fec_drv_remove() error: Using fep after free_{netdev,candev}(ndev);
	drivers/net/ethernet/freescale/fec_main.c:3995 fec_drv_remove() error: Using fep after free_{netdev,candev}(ndev);

Since fep pointer is netdev private data, accessing it after free_netdev()
call can cause use-after-free bug. Fix it by moving free_netdev() call at
the end of the function

Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Fixes: a31eda65ba21 ("net: fec: fix clock count mis-match")
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
---
 drivers/net/ethernet/freescale/fec_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 8aea707a65a7..7e4c4980ced7 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -3843,13 +3843,13 @@ fec_drv_remove(struct platform_device *pdev)
 	if (of_phy_is_fixed_link(np))
 		of_phy_deregister_fixed_link(np);
 	of_node_put(fep->phy_node);
-	free_netdev(ndev);
 
 	clk_disable_unprepare(fep->clk_ahb);
 	clk_disable_unprepare(fep->clk_ipg);
 	pm_runtime_put_noidle(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 
+	free_netdev(ndev);
 	return 0;
 }
 
-- 
2.32.0