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

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Message-ID: <CAGXu5jKpmw2qEqL7dnELS5h45pq9AZf=0nEXox52qEbP6pz4CA@mail.gmail.com>
Date:   Tue, 27 Feb 2018 14:59:33 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Danilo Krummrich <danilokrummrich@...develop.de>
Cc:     "Luis R. Rodriguez" <mcgrof@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH 2/2] fs/sysctl: remove redundant link check in proc_sys_link_fill_cache()

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

> +       if (err)
> +               goto out;
>
>         ret = proc_sys_fill_cache(file, ctx, head, table);
>  out:
> --
> 2.14.1
>



-- 
Kees Cook
Pixel Security