netdev - Re: [PATCH] net/mlx4_en: fix off by one in error handling

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Date:   Wed, 14 Sep 2016 16:43:33 +0300
From:   Tariq Toukan <ttoukan.linux@...il.com>
To:     Sebastian Ott <sebott@...ux.vnet.ibm.com>,
        Yishai Hadas <yishaih@...lanox.com>,
        Tariq Toukan <tariqt@...lanox.com>
Cc:     netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net/mlx4_en: fix off by one in error handling

Hi Sebastian,

Thanks for this fix.

On 14/09/2016 2:09 PM, Sebastian Ott wrote:
> If an error occurs in mlx4_init_eq_table the index used in the
> err_out_unmap label is one too big which results in a panic in
> mlx4_free_eq. This patch fixes the index in the error path.
You are right, but your change below does not cover all cases.
The full solution looks like this:

@@ -1260,7 +1260,7 @@ int mlx4_init_eq_table(struct mlx4_dev *dev)
                                              eq);
                 }
                 if (err)
-                       goto err_out_unmap;
+                       goto err_out_unmap_excluded;
         }

         if (dev->flags & MLX4_FLAG_MSI_X) {
@@ -1306,8 +1306,10 @@ int mlx4_init_eq_table(struct mlx4_dev *dev)
         return 0;

  err_out_unmap:
-       while (i >= 0)
-               mlx4_free_eq(dev, &priv->eq_table.eq[i--]);
+       mlx4_free_eq(dev, &priv->eq_table.eq[i]);
+err_out_unmap_excluded:
+       while (i > 0)
+               mlx4_free_eq(dev, &priv->eq_table.eq[--i]);
  #ifdef CONFIG_RFS_ACCEL
         for (i = 1; i <= dev->caps.num_ports; i++) {
                 if (mlx4_priv(dev)->port[i].rmap) {


>
> Signed-off-by: Sebastian Ott <sebott@...ux.vnet.ibm.com>
> ---
>   drivers/net/ethernet/mellanox/mlx4/eq.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/eq.c b/drivers/net/ethernet/mellanox/mlx4/eq.c
> index f613977..cf8f8a7 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/eq.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/eq.c
> @@ -1305,8 +1305,8 @@ int mlx4_init_eq_table(struct mlx4_dev *dev)
>   	return 0;
>   
>   err_out_unmap:
> -	while (i >= 0)
> -		mlx4_free_eq(dev, &priv->eq_table.eq[i--]);
> +	while (i > 0)
> +		mlx4_free_eq(dev, &priv->eq_table.eq[--i]);
>   #ifdef CONFIG_RFS_ACCEL
>   	for (i = 1; i <= dev->caps.num_ports; i++) {
>   		if (mlx4_priv(dev)->port[i].rmap) {
You can choose to submit again, or we can take it from here. Whatever 
you prefer.

Regards,
Tariq