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([2a01:e0a:9b4:d000:c3c5:df83:3a33:2c51]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6a09c6551cbsm373196a12.20.2026.07.31.00.19.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 31 Jul 2026 00:19:30 -0700 (PDT) Message-ID: Date: Fri, 31 Jul 2026 09:19:26 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] drm/log: Fix division by zero when scale module parameter is 0 To: oushixiong1025@163.com Cc: Javier Martinez Canillas , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Jani Nikula , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Shixiong Ou References: <20260730014440.66323-1-oushixiong1025@163.com> Content-Language: en-US, fr From: Jocelyn Falempe In-Reply-To: <20260730014440.66323-1-oushixiong1025@163.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 30/07/2026 03:44, oushixiong1025@163.com wrote: > From: Shixiong Ou > > The scale module parameter can be set to 0 via kernel command line. > When scale is 0, scaled_font_h and scaled_font_w become 0, causing > a division by zero in the rows/columns calculation. > > Since the scale module parameter is read-only (0444 permissions), it > cannot be changed at runtime via sysfs. Clamp it to 1 once in > drm_log_register(). Thanks, it looks good to me Reviewed-by: Jocelyn Falempe > > Signed-off-by: Shixiong Ou > --- > v2->v3: > Clamp scale once in drm_log_register() instead of introducing a > drm_log_scale() helper, since scale is read-only at runtime. > > v1->v2: > Introduce a drm_log_scale() helper. > > diff --git a/drivers/gpu/drm/clients/drm_log.c b/drivers/gpu/drm/clients/drm_log.c > index 294b3be1a6b3..46004abd4e61 100644 > --- a/drivers/gpu/drm/clients/drm_log.c > +++ b/drivers/gpu/drm/clients/drm_log.c > @@ -424,6 +424,9 @@ void drm_log_register(struct drm_device *dev) > { > struct drm_log *new; > > + if (!scale) > + scale = 1; > + > new = kzalloc_obj(*new); > if (!new) > goto err_warn; > -- > 2.25.1 > > No virus found > Checked by Hillstone Network AntiVirus >