linux-kernel - Re: [PATCH] seccomp: fix poor type promotion

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Message-ID: <CAGXu5jL0L16BNK1SouaG32FJ_mJECUrJfMNRH6pWdG0Be8a-ZQ@mail.gmail.com>
Date:   Thu, 13 Dec 2018 16:48:46 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Tycho Andersen <tycho@...ho.ws>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] seccomp: fix poor type promotion

On Wed, Dec 12, 2018 at 6:47 PM Tycho Andersen <tycho@...ho.ws> wrote:
>
> sparse complains,
>
> kernel/seccomp.c:1172:13: warning: incorrect type in assignment (different base types)
> kernel/seccomp.c:1172:13:    expected restricted __poll_t [usertype] ret
> kernel/seccomp.c:1172:13:    got int
> kernel/seccomp.c:1173:13: warning: restricted __poll_t degrades to integer
>
> Instead of assigning this to ret, since we don't use this anywhere, let's
> just test it against 0 directly.
>
> Signed-off-by: Tycho Andersen <tycho@...ho.ws>
> Reported-by: 0day robot <lkp@...el.com>

Thanks! Added to my -next tree.

-Kees

> ---
>  kernel/seccomp.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/kernel/seccomp.c b/kernel/seccomp.c
> index 15b6be97fc09..d7f538847b84 100644
> --- a/kernel/seccomp.c
> +++ b/kernel/seccomp.c
> @@ -1169,8 +1169,7 @@ static __poll_t seccomp_notify_poll(struct file *file,
>
>         poll_wait(file, &filter->notif->wqh, poll_tab);
>
> -       ret = mutex_lock_interruptible(&filter->notify_lock);
> -       if (ret < 0)
> +       if (mutex_lock_interruptible(&filter->notify_lock) < 0)
>                 return EPOLLERR;
>
>         list_for_each_entry(cur, &filter->notif->notifications, list) {
> --
> 2.19.1
>


-- 
Kees Cook