[PATCH 5.4 32/85] net: fec: fix use-after-free in fec_drv_remove

Greg Kroah-Hartman
2021-08-10T17:36:01Z

From: Pavel Skripkin <paskripkin@gmail.com>

[ Upstream commit 44712965bf12ae1758cec4de53816ed4b914ca1a ]

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@oracle.com>
Fixes: a31eda65ba21 ("net: fec: fix clock count mis-match")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Reviewed-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 b1856552ab81..a53c2d637a97 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -3781,13 +3781,13 @@ 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;
}

--
2.30.2