linux-kernel - Re: [PATCH v2] drm/gud: Use kmalloc

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Message-ID: <26036ff3-2374-40a9-8597-271b93130a7e@suse.de>
Date: Tue, 7 Oct 2025 09:45:15 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>,
 maarten.lankhorst@...ux.intel.com, mripard@...nel.org, airlied@...il.com,
 simona@...ll.ch, mingo@...nel.org, tglx@...utronix.de, jfalempe@...hat.com,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 linux-kernel-mentees@...ts.linuxfoundation.org, skhan@...uxfoundation.org,
 david.hunter.linux@...il.com, rubenru09@....com
Subject: Re: [PATCH v2] drm/gud: Use kmalloc_array() instead of kmalloc()

Hi

Am 23.09.25 um 10:51 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' to avoid
> overflow.
>
> Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
> ---
> Changelog:
>
> Changes since v1:
> - Use of width as element count and height as size of element to
> eliminate the mentionned calculation and overflow issues.
>
>   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..8898dc9393fb 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, GFP_KERNEL);

One nitpick here: the first parameter is the number of elements and the 
second parameter is the size of an individual element. [1] So the 
arguments 'width' and 'height' should be reversed.  Please resubmit.

Best regards
Thomas

[1] 
https://elixir.bootlin.com/linux/v6.17.1/source/tools/include/linux/slab.h#L15

>   	if (!buf)
>   		return 0;
>   

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)