linux-kernel - Re: [PATCH 2/2] fs/sysctl: remove redundant link check in proc_sys_link_fill

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Date:   Wed, 28 Feb 2018 00:01:17 +0100
From:   Danilo Krummrich <danilokrummrich@...develop.de>
To:     Kees Cook <keescook@...omium.org>
Cc:     "Luis R. Rodriguez" <mcgrof@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-fsdevel@...r.kernel.org, keescook@...gle.com
Subject: Re: [PATCH 2/2] fs/sysctl: remove redundant link check in
 proc_sys_link_fill_cache()

On 2018-02-27 23:59, Kees Cook wrote:
> On Tue, Feb 27, 2018 at 2:43 PM, Danilo Krummrich
> <danilokrummrich@...develop.de> wrote:
>> proc_sys_link_fill_cache() does not need to check whether we're
>> called for a link - it's already done by scan().
>> 
>> Signed-off-by: Danilo Krummrich <danilokrummrich@...develop.de>
>> ---
>>  fs/proc/proc_sysctl.c | 11 +++++------
>>  1 file changed, 5 insertions(+), 6 deletions(-)
>> 
>> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
>> index a0b6c647835e..7e7d9facb842 100644
>> --- a/fs/proc/proc_sysctl.c
>> +++ b/fs/proc/proc_sysctl.c
>> @@ -707,17 +707,16 @@ static bool proc_sys_link_fill_cache(struct file 
>> *file,
>>                                     struct ctl_table *table)
>>  {
>>         bool ret = true;
>> +       int err = 0;
>>         head = sysctl_head_grab(head);
>> 
>>         if (IS_ERR(head))
>>                 return false;
>> 
>> -       if (S_ISLNK(table->mode)) {
>> -               /* It is not an error if we can not follow the link 
>> ignore it */
>> -               int err = sysctl_follow_link(&head, &table);
>> -               if (err)
>> -                       goto out;
>> -       }
>> +       /* It is not an error if we can not follow the link ignore it 
>> */
>> +       sysctl_follow_link(&head, &table);
> 
> Shouldn't this be err = sysctl_follow_link... ? Otherwise I don't see
> where err is used.
> 
> -Kees
> 
Of course, thanks.
>> +       if (err)
>> +               goto out;
>> 
>>         ret = proc_sys_fill_cache(file, ctx, head, table);
>>  out:
>> --
>> 2.14.1
>>