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
ad297cd ("net: qcom/emac: fix UAF in emac_remove").

This bug is detected by our static analysis tool.

Fixes: cf9e60a ("net: davicom: Fix regulator not turned off on driver removal")
Signed-off-by: Chenyuan Yang <[email protected]>
CC: Uwe Kleine-König <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: WhiteFox-Project

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");
 }