linux-kernel - Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function.

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Message-ID: <20161122165017.GC31595@intel.com>
Date:   Tue, 22 Nov 2016 18:50:17 +0200
From:   Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:     Liviu Dudau <Liviu.Dudau@....com>
Cc:     Eric Engestrom <eric@...estrom.ch>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        LKML <linux-kernel@...r.kernel.org>,
        DRI devel <dri-devel@...ts.freedesktop.org>,
        Jani Nikula <jani.nikula@...el.com>
Subject: Re: [PATCH] drm: check for NULL parameter in exported
 drm_get_format_name() function.

On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote:
> drm_get_format_name() de-references the buf parameter without checking
> if the pointer was not NULL. Given that the function is EXPORT-ed, lets
> sanitise the parameters before proceeding.
> 
> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name())
> Cc: Eric Engestrom <eric@...estrom.ch>
> Cc: Rob Clark <robdclark@...il.com>
> Cc: Jani Nikula <jani.nikula@...el.com>
> Cc: Daniel Vetter <daniel.vetter@...ll.ch>
> 
> Signed-off-by: Liviu Dudau <Liviu.Dudau@....com>
> ---
>  drivers/gpu/drm/drm_fourcc.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> index 90d2cc8..0a3ff0b 100644
> --- a/drivers/gpu/drm/drm_fourcc.c
> +++ b/drivers/gpu/drm/drm_fourcc.c
> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format);
>   */
>  const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf)
>  {
> +	if (!buf)
> +		return NULL;
> +

Seems rather pointless to me. Why would you ever pass NULL to this guy?

>  	snprintf(buf->str, sizeof(buf->str),
>  		 "%c%c%c%c %s-endian (0x%08x)",
>  		 printable_char(format & 0xff),
> -- 
> 2.10.2
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Ville Syrjälä
Intel OTC

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