From mboxrd@z Thu Jan  1 00:00:00 1970
From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Mon, 20 Oct 2014 07:10:37 +0000
Subject: Re: [PATCH 3/5] video: fbdev: uvesafb.c: Cleaning up missing null-terminate by switching from strncp
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References: <1413670496-6387-1-git-send-email-rickard_strandqvist@spectrumdigital.se>
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To: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Cc: Michal Januszewski <spock@gentoo.org>, Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>, Andi Kleen <ak@linux.intel.com>, Andrew Morton <akpm@linux-foundation.org>, Dan Carpenter <dan.carpenter@oracle.com>, Grant Likely <grant.likely@linaro.org>, Tomi Valkeinen <tomi.valkeinen@ti.com>, Linux Fbdev development list <linux-fbdev@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>

On Sun, Oct 19, 2014 at 12:14 AM, Rickard Strandqvist
<rickard_strandqvist@spectrumdigital.se> wrote:
> Ensures that the string is null-terminate in connection with the
> use of strncpy, by switching from strncpy to strzcpy.
>
> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
> ---
>  drivers/video/fbdev/uvesafb.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/uvesafb.c b/drivers/video/fbdev/uvesafb.c
> index 509d452..3383b34 100644
> --- a/drivers/video/fbdev/uvesafb.c
> +++ b/drivers/video/fbdev/uvesafb.c
> @@ -1892,7 +1892,7 @@ static ssize_t show_v86d(struct device_driver *dev, char *buf)
>  static ssize_t store_v86d(struct device_driver *dev, const char *buf,
>                 size_t count)
>  {
> -       strncpy(v86d_path, buf, PATH_MAX);
> +       strzcpy(v86d_path, buf, sizeof(v86d_path));

I think strlcpy() should be good enough here?
Or am I missing a reason why the rest of the buffer should be zero-filled?

Nevertheless, I think this (or an alternative) change should be applied to
stable, as call_usermodehelper() might crash by writing to sysfs.

>         return count;
>  }

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds