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

Tariq Toukan
2016-09-15T12:18:32Z

On 14/09/2016 7:08 PM, Sebastian Ott wrote:
> On Wed, 14 Sep 2016, Tariq Toukan wrote:
>> On 14/09/2016 4:53 PM, Sebastian Ott wrote:
>>> On Wed, 14 Sep 2016, Tariq Toukan wrote:
>>>> 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;
>>> In this case a call to mlx4_create_eq failed. Do you really have to call
>>> mlx4_free_eq for this index again?
>> We agree on this part, that's why here we should goto the _excluded_ label.
>> For all other parts, we should not exclude the eq in the highest index, and
>> thus we goto the _non_excluded_ label.
> But that's exactly what the original patch does. If the failure is within
> the for loop at index i, we do the cleanup starting at index i-1. If the
> failure is after the for loop then i == dev->caps.num_comp_vectors + 1
> and we do the cleanup starting at index i == dev->caps.num_comp_vectors.
>
> In the latter case your patch would have an out of bounds array access.
Indeed. Agreed.

> Regards,
> Sebastian
>

Reviewed-by: Tariq Toukan <tariqt@mellanox.com>

Thanks!