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Wed, 13 May 2026 14:00:37 -0700 (PDT) Date: Wed, 13 May 2026 14:00:33 -0700 From: Dmitry Torokhov To: Ranjan Kumar Cc: bleung@chromium.org, dusonlin@emc.com.tw, bentiss@kernel.org, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Input: elan_i2c - prevent division by zero on invalid device parameters Message-ID: References: <20260513073908.3326178-1-kumarranja@chromium.org> Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260513073908.3326178-1-kumarranja@chromium.org> Hi Ranjan, On Wed, May 13, 2026 at 07:39:08AM +0000, Ranjan Kumar wrote: > The Elan I2C touchpad driver queries the device for its physical > dimensions and trace counts to calculate the device resolution and width. > However, if the device firmware or device tree provides invalid zero > values for x_traces, y_traces, x_mm, or y_mm, it results in a fatal > division-by-zero exception leading to a kernel panic during device probe. > Neither crashing nor aborting probe with -EINVAL is great as we will not be able to flash another firmware. How do we get into this state? Is this something actually observed or just theoretical? > Add sanity checks to ensure these physical parameters are non-zero > before performing the division. If invalid values are detected, log an > error and return -EINVAL to gracefully abort the initialization and > maintain system stability. That is hardly "stability" for a laptop when its pointer is not working. Thanks. -- Dmitry