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Sun, 19 Oct 2025 08:03:50 -0700 (PDT) Received: from [192.168.1.105] ([165.50.121.102]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-63c48a92961sm4345576a12.8.2025.10.19.08.03.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 19 Oct 2025 08:03:50 -0700 (PDT) Message-ID: Date: Sun, 19 Oct 2025 17:03:42 +0100 Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drm/tiny: Use kmalloc_array() instead of kmalloc() To: Thomas Zimmermann , Greg KH Cc: lanzano.alex@gmail.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, airlied@gmail.com, simona@ffwll.ch, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, david.hunter.linux@gmail.com, khalid@kernel.org, linux-kernel-mentees@lists.linuxfoundation.org References: <20251019151247.171558-1-mehdi.benhadjkhelifa@gmail.com> <2025101910-dipper-suburb-1755@gregkh> Content-Language: en-US From: Mehdi Ben Hadj Khelifa In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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 >>> --- >>>   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)