net/mlx5e/core/en_fs: fix pointer dereference after free in mlx5e_execute_l2_action

hn is being kfree'd in mlx5e_del_l2_from_hash and then dereferenced
by accessing hn->ai.addr

Fix this by copying the MAC address into a local variable for its safe use
in all possible execution paths within function mlx5e_execute_l2_action.

Addresses-Coverity-ID: 1417789
Fixes: eeb66cdb6826 ("net/mlx5: Separate between E-Switch and MPFS")
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_fs.c b/drivers/net/ethernet/mellanox/mlx5/core/en_fs.c
index 850cdc9..4837045 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_fs.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_fs.c
@@ -365,21 +365,24 @@ static void mlx5e_execute_l2_action(struct mlx5e_priv *priv,
                                    struct mlx5e_l2_hash_node *hn)
 {
        u8 action = hn->action;
+       u8 mac_addr[ETH_ALEN];
        int l2_err = 0;
 
+       ether_addr_copy(mac_addr, hn->ai.addr);
+
        switch (action) {
        case MLX5E_ACTION_ADD:
                mlx5e_add_l2_flow_rule(priv, &hn->ai, MLX5E_FULLMATCH);
-               if (!is_multicast_ether_addr(hn->ai.addr)) {
-                       l2_err = mlx5_mpfs_add_mac(priv->mdev, hn->ai.addr);
+               if (!is_multicast_ether_addr(mac_addr)) {
+                       l2_err = mlx5_mpfs_add_mac(priv->mdev, mac_addr);
                        hn->mpfs = !l2_err;
                }
                hn->action = MLX5E_ACTION_NONE;
                break;
 
        case MLX5E_ACTION_DEL:
-               if (!is_multicast_ether_addr(hn->ai.addr) && hn->mpfs)
-                       l2_err = mlx5_mpfs_del_mac(priv->mdev, hn->ai.addr);
+               if (!is_multicast_ether_addr(mac_addr) && hn->mpfs)
+                       l2_err = mlx5_mpfs_del_mac(priv->mdev, mac_addr);
                mlx5e_del_l2_flow_rule(priv, &hn->ai);
                mlx5e_del_l2_from_hash(hn);
                break;
@@ -387,7 +390,7 @@ static void mlx5e_execute_l2_action(struct mlx5e_priv *priv,
 
        if (l2_err)
                netdev_warn(priv->netdev, "MPFS, failed to %s mac %pM, err(%d)\n",
-                           action == MLX5E_ACTION_ADD ? "add" : "del", hn->ai.addr, l2_err);
+                           action == MLX5E_ACTION_ADD ? "add" : "del", mac_addr, l2_err);
 }
 
 static void mlx5e_sync_netdev_addr(struct mlx5e_priv *priv)