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

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Message-ID: <CAF6AEGs=W8Me6T1qLiq2UEoWQg2+eYNRvw+5W11CXM7CAYBZKg@mail.gmail.com>
Date:   Tue, 22 Nov 2016 12:23:59 -0500
From:   Rob Clark <robdclark@...il.com>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:     Liviu Dudau <Liviu.Dudau@....com>,
        Jani Nikula <jani.nikula@...el.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Eric Engestrom <eric@...estrom.ch>,
        LKML <linux-kernel@...r.kernel.org>,
        DRI devel <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH] drm: check for NULL parameter in exported
 drm_get_format_name() function.

On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä
<ville.syrjala@...ux.intel.com> wrote:
> 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?

perhaps BUG_ON(!buf)...

BR,
-R

>>       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
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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