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>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_fs.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

On Sat, Nov 4, 2017 at 8:54 PM, Gustavo A. R. Silva
<garsilva@embeddedor.com> wrote:
> 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>

Looks good.
Thank you Gustavo.

> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en_fs.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
>
> 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
> --- 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)
> --
> 2.7.4
>
> --
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Hi Saeed,

Quoting Saeed Mahameed <saeedm@dev.mellanox.co.il>:

> On Sat, Nov 4, 2017 at 8:54 PM, Gustavo A. R. Silva
> <garsilva@embeddedor.com> wrote:
>> 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>
>
> Looks good.
> Thank you Gustavo.
>

Glad to help.

Thanks
--
Gustavo A. R. Silva

From: "Gustavo A. R. Silva" <garsilva@embeddedor.com>
Date: Sat, 4 Nov 2017 22:54:53 -0500

> 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>

Applied and queued up for -stable, thanks.

Quoting David Miller <davem@davemloft.net>:

> From: "Gustavo A. R. Silva" <garsilva@embeddedor.com>
> Date: Sat, 4 Nov 2017 22:54:53 -0500
>
>> 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>
>
> Applied and queued up for -stable, thanks.

Awesome. Thanks!

--
Gustavo A. R. Silva