[PATCH net v2] net: davicom: fix UAF in dm9000_drv_remove

[PATCH net v2] net: davicom: fix UAF in dm9000_drv_remove

[Chenyuan Yang]

This bug is detected by our static analysis tool.

dm is netdev private data and it cannot be
used after free_netdev() call. Using dm after free_netdev()
can cause UAF bug. Fix it by moving free_netdev() at the end of the
function.

This is similar to the issue fixed in commit
ad297cd2db89 ("net: qcom/emac: fix UAF in emac_remove").

Fixes: cf9e60aa69ae ("net: davicom: Fix regulator not turned off on driver removal")
Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
CC: Paolo Abeni <pabeni@redhat.com>
CC: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 drivers/net/ethernet/davicom/dm9000.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/davicom/dm9000.c b/drivers/net/ethernet/davicom/dm9000.c
index 8735e333034c..b87eaf0c250c 100644
--- a/drivers/net/ethernet/davicom/dm9000.c
+++ b/drivers/net/ethernet/davicom/dm9000.c
@@ -1777,10 +1777,11 @@ static void dm9000_drv_remove(struct platform_device *pdev)
 
 	unregister_netdev(ndev);
 	dm9000_release_board(pdev, dm);
-	free_netdev(ndev);		/* free device structure */
 	if (dm->power_supply)
 		regulator_disable(dm->power_supply);
 
+	free_netdev(ndev);		/* free device structure */
+
 	dev_dbg(&pdev->dev, "released and freed device\n");
 }
 
-- 
2.34.1

Re: [PATCH net v2] net: davicom: fix UAF in dm9000_drv_remove

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 23 Jan 2025 15:42:13 -0600 you wrote:
> This bug is detected by our static analysis tool.
> 
> dm is netdev private data and it cannot be
> used after free_netdev() call. Using dm after free_netdev()
> can cause UAF bug. Fix it by moving free_netdev() at the end of the
> function.
> 
> [...]

Here is the summary with links:
  - [net,v2] net: davicom: fix UAF in dm9000_drv_remove
    https://git.kernel.org/netdev/net/c/19e65c45a150

You are awesome, thank you!
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