On Sun, 19 Oct 2025, Mehdi Ben Hadj Khelifa <[email protected]> wrote: > 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 <[email protected]> >>>> --- >>>> 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);
Also worth emphasizing that this is wildly wrong for any height that is not a multiple of 8. And I thought I shot down a similar patch not long ago. Is there some tool that suggests doing this? Fix the tool instead please. BR, Jani. >>> 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) > -- Jani Nikula, Intel
