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Mon, 13 Jan 2025 00:26:43 -0800 (PST) X-Google-Smtp-Source: AGHT+IGwZgHFVxFYDB23A1IPJkQKxFc9ZJ96CwJeYtxTwoXAyP1H7xIscXWZlEGhswvTIelsRuJzkw== X-Received: by 2002:a17:907:6d1a:b0:aaf:ab71:69cd with SMTP id a640c23a62f3a-ab2ab558b75mr1917635266b.20.1736756802963; Mon, 13 Jan 2025 00:26:42 -0800 (PST) Received: from [10.40.98.179] ([78.108.130.194]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ab2c90d7432sm464991866b.49.2025.01.13.00.26.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Jan 2025 00:26:42 -0800 (PST) Message-ID: Date: Mon, 13 Jan 2025 09:26:41 +0100 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 v2] platform/x86: dell-uart-backlight: fix NULL pointer dereference in probe To: Chenyuan Yang , ilpo.jarvinen@linux.intel.com, rafael.j.wysocki@intel.com, acelan.kao@canonical.com, u.kleine-koenig@baylibre.com Cc: platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org, zijie98@gmail.com References: <20250111180118.2274516-1-chenyuan0y@gmail.com> Content-Language: en-US From: Hans de Goede In-Reply-To: <20250111180118.2274516-1-chenyuan0y@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, On 11-Jan-25 7:01 PM, Chenyuan Yang wrote: > The dell_uart_bl_serdev_probe() function calls devm_serdev_device_open() > before setting the client ops via serdev_device_set_client_ops(). This > ordering can trigger a NULL pointer dereference in the serdev controller's > receive_buf handler, as it assumes serdev->ops is valid when > SERPORT_ACTIVE is set. > > This is similar to the issue fixed in commit 5e700b384ec1 > ("platform/chrome: cros_ec_uart: properly fix race condition") where > devm_serdev_device_open() was called before fully initializing the > device. > > Fix the race by ensuring client ops are set before enabling the port via > devm_serdev_device_open(). > Note, serdev_device_set_baudrate() and > serdev_device_set_flow_control() calls should be > after the devm_serdev_device_open() call. > > Fixes: 484bae9e4d6a ("platform/x86: Add new Dell UART backlight driver") > Signed-off-by: Chenyuan Yang > CC: Hans de Goede Thanks, patch looks good to me: Reviewed-by: Hans de Goede Regards, Hans > --- > drivers/platform/x86/dell/dell-uart-backlight.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/platform/x86/dell/dell-uart-backlight.c b/drivers/platform/x86/dell/dell-uart-backlight.c > index 6e5dc7e3674f..bcc5c0f3bb4d 100644 > --- a/drivers/platform/x86/dell/dell-uart-backlight.c > +++ b/drivers/platform/x86/dell/dell-uart-backlight.c > @@ -283,6 +283,9 @@ static int dell_uart_bl_serdev_probe(struct serdev_device *serdev) > init_waitqueue_head(&dell_bl->wait_queue); > dell_bl->dev = dev; > > + serdev_device_set_drvdata(serdev, dell_bl); > + serdev_device_set_client_ops(serdev, &dell_uart_bl_serdev_ops); > + > ret = devm_serdev_device_open(dev, serdev); > if (ret) > return dev_err_probe(dev, ret, "opening UART device\n"); > @@ -290,8 +293,6 @@ static int dell_uart_bl_serdev_probe(struct serdev_device *serdev) > /* 9600 bps, no flow control, these are the default but set them to be sure */ > serdev_device_set_baudrate(serdev, 9600); > serdev_device_set_flow_control(serdev, false); > - serdev_device_set_drvdata(serdev, dell_bl); > - serdev_device_set_client_ops(serdev, &dell_uart_bl_serdev_ops); > > get_version[0] = DELL_SOF(GET_CMD_LEN); > get_version[1] = CMD_GET_VERSION;