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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <d072dfe7-e0e9-49f6-89ed-25d194035e3b@gmail.com>
Date: Sun, 19 Oct 2025 17:03:42 +0100
From: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
To: Thomas Zimmermann <tzimmermann@...e.de>,
 Greg KH <gregkh@...uxfoundation.org>
Cc: lanzano.alex@...il.com, maarten.lankhorst@...ux.intel.com,
 mripard@...nel.org, airlied@...il.com, simona@...ll.ch,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 skhan@...uxfoundation.org, david.hunter.linux@...il.com, khalid@...nel.org,
 linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH] drm/tiny: Use kmalloc_array() instead of kmalloc()

On 10/19/25 3:47 PM, Thomas Zimmermann wrote:
> Hi
> 
> Am 19.10.25 um 16:34 schrieb Greg KH:
>> On Sun, Oct 19, 2025 at 04:12:28PM +0100, Mehdi Ben Hadj Khelifa wrote:
>>> Replace kmalloc() with kmalloc_array() to correctly
>>> handle array allocations and benefit from built-in overflow checking[1].
>>>
>>> [1]:https://docs.kernel.org/process/deprecated.html
>>>
>>> Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
>>> ---
>>>   drivers/gpu/drm/tiny/repaper.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/tiny/repaper.c b/drivers/gpu/drm/tiny/ 
>>> repaper.c
>>> index 4824f863fdba..290132c24ff9 100644
>>> --- a/drivers/gpu/drm/tiny/repaper.c
>>> +++ b/drivers/gpu/drm/tiny/repaper.c
>>> @@ -534,7 +534,7 @@ static int repaper_fb_dirty(struct 
>>> drm_framebuffer *fb, const struct iosys_map *
>>>       DRM_DEBUG("Flushing [FB:%d] st=%ums\n", fb->base.id,
>>>             epd->factored_stage_time);
>>> -    buf = kmalloc(fb->width * fb->height / 8, GFP_KERNEL);
>>> +    buf = kmalloc_array(fb->height / 8, fb->width, GFP_KERNEL);
>> This isn't an array, so this function change doesn't seem to make much
>> sense, right?  The size should have already been checked earlier in the
>> call change to be correct.
Yes,I was intending to say framebuffer but I was working on another 
similar patch simultaneously so I reused same words by mistake. Thanks 
for clarifying that.>
> Yes, we've recently received plenty of these pointless changes. The 
> correct code would compute the number of bytes per pixel using 
> drm_format_info_min_pitch() and multiply with fb->height. The latter 
> could (maybe) use kmalloc_array(). It would still not be an array in the 
> common sense.
> 
Thanks for the review and suggestion.I will be sending a v2 patch with 
the recommended code change.

Best Regards,
Mehdi Ben Hadj Khelifa> Best regards
> Thomas
> 
>>
>> thanks,
>>
>> greg k-h
> 
> -- 
> -- 
> 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)