Re: [PATCH] drm/gud: Use kmalloc_array() instead of kmalloc()

Thomas Zimmermann
2025-09-23T07:06:16Z

Hi

Am 23.09.25 um 08:34 schrieb Thomas Zimmermann:
> cc Ruben
>
> Am 22.09.25 um 19:43 schrieb Mehdi Ben Hadj Khelifa:
>> Replace kmalloc with kmalloc array in drm/gud/gud_pipe.c since the
>> calculation inside kmalloc is dynamic "width * height" and added
>> u_char as the size of each element.
>>
>> Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@gmail.com>
>> ---
>>   drivers/gpu/drm/gud/gud_pipe.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/gud/gud_pipe.c
>> b/drivers/gpu/drm/gud/gud_pipe.c
>> index 8d548d08f127..eeea0cb4c7aa 100644
>> --- a/drivers/gpu/drm/gud/gud_pipe.c
>> +++ b/drivers/gpu/drm/gud/gud_pipe.c
>> @@ -70,7 +70,7 @@ static size_t gud_xrgb8888_to_r124(u8 *dst, const
>> struct drm_format_info *format
>>       height = drm_rect_height(rect);
>>       len = drm_format_info_min_pitch(format, 0, width) * height;
>>   -    buf = kmalloc(width * height, GFP_KERNEL);
>> +    buf = kmalloc_array(width * height, sizeof(u_char), GFP_KERNEL);

u_char is more or less guaranteed to be 8 bit. So what's the point?

There's a potential overflow in width * height. If anything, you want to
call kmalloc_array(height, width).

Best regards
Thomas

>>       if (!buf)
>>           return 0;
>

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
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