linux-kernel - Re: [PATCH] ptp: drop redundant kasprintf() to create worker name

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Message-ID: <CAGXu5jKj6UWOHrJ-13WQf918sZFe7+gwjAErpu22pLZjdGAZKA@mail.gmail.com>
Date:   Sun, 28 Oct 2018 16:05:09 +0000
From:   Kees Cook <keescook@...omium.org>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     Richard Cochran <richardcochran@...il.com>,
        Network Development <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ptp: drop redundant kasprintf() to create worker name

On Fri, Oct 26, 2018 at 10:22 PM, Rasmus Villemoes
<linux@...musvillemoes.dk> wrote:
> Building with -Wformat-nonliteral, gcc complains
>
> drivers/ptp/ptp_clock.c: In function ‘ptp_clock_register’:
> drivers/ptp/ptp_clock.c:239:26: warning: format not a string literal and no format arguments [-Wformat-nonliteral]
>             worker_name : info->name);
>
> kthread_create_worker takes fmt+varargs to set the name of the
> worker, and that happens with a vsnprintf() to a stack buffer (that is
> then copied into task_comm). So there's no reason not to just pass
> "ptp%d", ptp->index to kthread_create_worker() and avoid the
> intermediate worker_name variable.
>
> Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  drivers/ptp/ptp_clock.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
> index 7eacc1c4b3b1..5419a89d300e 100644
> --- a/drivers/ptp/ptp_clock.c
> +++ b/drivers/ptp/ptp_clock.c
> @@ -232,12 +232,8 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
>         init_waitqueue_head(&ptp->tsev_wq);
>
>         if (ptp->info->do_aux_work) {
> -               char *worker_name = kasprintf(GFP_KERNEL, "ptp%d", ptp->index);
> -
>                 kthread_init_delayed_work(&ptp->aux_work, ptp_aux_kworker);
> -               ptp->kworker = kthread_create_worker(0, worker_name ?
> -                                                    worker_name : info->name);
> -               kfree(worker_name);
> +               ptp->kworker = kthread_create_worker(0, "ptp%d", ptp->index);
>                 if (IS_ERR(ptp->kworker)) {
>                         err = PTR_ERR(ptp->kworker);
>                         pr_err("failed to create ptp aux_worker %d\n", err);
> --
> 2.19.1.6.gbde171bbf5
>



-- 
Kees Cook