net/mlx4: prevent potential use after free in mlx4_en_do_uc_filter()

[ Upstream commit 4f0d91ba72811fd5dd577bcdccd7fed649aae62c ]

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@linaro.org>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/aNvMHX4g8RksFFvV@stanley.mountain
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
index ca4b93a0103469b9629dad2f877a496c23fd727c..e66f77af677cfafbb94b65e10a74d4d5699e0763 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
@@ -1177,9 +1177,9 @@ 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;
                        }
                }