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

[Michal Swiatkowski]

On Mon, Jan 20, 2025 at 04:25:57PM -0600, Chenyuan Yang wrote:
> dm is netdev private data and it cannot be
> used after free_netdev() call. Using adpt 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
> ad297cd2db8953e2202970e9504cab247b6c7cb4 ("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@xxxxxxxxx>
> ---
>  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");
>  }

Reviewed-by: Michal Swiatkowski <michal.swiatkowski@xxxxxxxxxxxxxxx>

>  
> -- 
> 2.34.1