net: davicom: fix UAF in dm9000_drv_remove

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").

This bug is detected by our static analysis tool.

Fixes: cf9e60aa69ae ("net: davicom: Fix regulator not turned off on driver removal")
Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
CC: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://patch.msgid.link/20250123214213.623518-1-chenyuan0y@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/davicom/dm9000.c b/drivers/net/ethernet/davicom/dm9000.c
index 8735e333034cf4bb07fe8a9b62f5a7e5ce2309d9..b87eaf0c250ce99b4b4043836a5a3b889c1b6be7 100644 (file)
--- 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");
 }