Re: [PATCH net] net/mlx4: prevent potential use after free in mlx4_en_do_uc_filter()

[Tariq Toukan]

On 30/09/2025 15:25, Dan Carpenter wrote:
> Print "entry->mac" before freeing "entry".  The "entry" pointer is
> freed with kfree_rcu() so it's unlikely that we would trigger this
> in real life, but it's safer to re-order it.
>
> Fixes: cc5387f7346a ("net/mlx4_en: Add unicast MAC filtering")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
>   drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> index d2071aff7b8f..308b4458e0d4 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> @@ -1180,9 +1180,9 @@ static void mlx4_en_do_uc_filter(struct mlx4_en_priv *priv,
>   				mlx4_unregister_mac(mdev->dev, priv->port, mac);
>   
>   				hlist_del_rcu(&entry->hlist);
> -				kfree_rcu(entry, rcu);
>   				en_dbg(DRV, priv, "Removed MAC %pM on port:%d\n",
>   				       entry->mac, priv->port);
> +				kfree_rcu(entry, rcu);
>   				++removed;
>   			}
>   		}

Reviewed-by: Tariq Toukan <tariqt@xxxxxxxxxx>

Thanks for your patch.