linux-kernel - Re: [PATCH] net/mlx5e/core/en_fs: fix pointer dereference after free in mlx5e_execute_l2

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Message-ID: <CALzJLG-YW_5AH__q2XHgaQM=xeLy+31LSeQdPAs7RhS=rLpJPw@mail.gmail.com>
Date:   Sat, 4 Nov 2017 21:43:14 -0700
From:   Saeed Mahameed <saeedm@....mellanox.co.il>
To:     "Gustavo A. R. Silva" <garsilva@...eddedor.com>
Cc:     Saeed Mahameed <saeedm@...lanox.com>,
        Matan Barak <matanb@...lanox.com>,
        Leon Romanovsky <leonro@...lanox.com>,
        Linux Netdev List <netdev@...r.kernel.org>,
        linux-rdma@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Jes Sorensen <jsorensen@...com>,
        Martin KaFai Lau <kafai@...com>
Subject: Re: [PATCH] net/mlx5e/core/en_fs: fix pointer dereference after free
 in mlx5e_execute_l2_action

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

Acked-by: Saeed Mahameed <saeedm@...lanox.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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