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

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Message-ID: <b2197c51-57a9-ab01-e940-9850a39484d6@gmail.com>
Date:   Wed, 14 Sep 2016 17:49:49 +0300
From:   Tariq Toukan <ttoukan.linux@...il.com>
To:     Sebastian Ott <sebott@...ux.vnet.ibm.com>
Cc:     Yishai Hadas <yishaih@...lanox.com>,
        Tariq Toukan <tariqt@...lanox.com>, 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



On 14/09/2016 4:53 PM, Sebastian Ott wrote:
> Hello Tariq,
>
> 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.
>   As far as I understood this code
> mlx4_create_eq cleans up when it fails and thus there is no need for an
> additional mlx4_free_eq call.
>
> Regards,
> Sebastian
>
Regards,
Tariq