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(unknown [183.174.60.14]) by APP-05 (Coremail) with SMTP id zQCowABnbysqetpnGlpAFg--.36380S2; Wed, 19 Mar 2025 16:03:00 +0800 (CST) From: Ma Ke To: mchehab@kernel.org, hverkuil@xs4all.nl, make24@iscas.ac.cn, sebastian.fricke@collabora.com, ribalda@chromium.org, benjamin.gaignard@collabora.com, viro@zeniv.linux.org.uk, bartosz.golaszewski@linaro.org, hljunggr@cisco.com, sakari.ailus@linux.intel.com Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v3] media: v4l2-dev: fix error handling in __video_register_device() Date: Wed, 19 Mar 2025 16:02:48 +0800 Message-Id: <20250319080248.1746847-1-make24@iscas.ac.cn> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: zQCowABnbysqetpnGlpAFg--.36380S2 X-Coremail-Antispam: 1UD129KBjvJXoW7WryrKw45Jr17XryrKrWDCFg_yoW8KF1kp3 4S9ay3tFWUKw4IkwsxXa1DXFyruw4Sy3WrArWrAw10k3s3urWfJry8tryUX3yUt392yF4j qry2qw4rXF1UZ3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUB214x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26ryj6F1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26F4UJVW0owA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1lnxkEFVAIw20F6cxK64vIFxWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xv F2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r 4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I 648v4I1lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7CjxVAaw2AFwI0_Jw0_GFyl42xK82IYc2 Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s02 6x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0x vE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE 42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6x kF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfUOmhFUUUUU X-CM-SenderInfo: ppdnvj2u6l2u1dvotugofq/ Content-Type: text/plain; charset="utf-8" Once device_register() failed, we should call put_device() to decrement reference count for cleanup. Or it could cause memory leak. And move callback function v4l2_device_release() and v4l2_device_get() before put_device(). As comment of device_register() says, 'NOTE: _Never_ directly free @dev after calling this function, even if it returned an error! Always use put_device() to give up the reference initialized in this function instead.' Found by code review. Cc: stable@vger.kernel.org Fixes: dc93a70cc7f9 ("V4L/DVB (9973): v4l2-dev: use the release callback fr= om device instead of cdev") Signed-off-by: Ma Ke Reviewed-by: Sakari Ailus --- Changes in v3: - modified the patch to balance the v4l2_device reference count; - changed the Fix tag as suggestions; Changes in v2: - modified the patch as no callback function before put_device(). --- drivers/media/v4l2-core/v4l2-dev.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v= 4l2-dev.c index 5bcaeeba4d09..4c7e1008a152 100644 --- a/drivers/media/v4l2-core/v4l2-dev.c +++ b/drivers/media/v4l2-core/v4l2-dev.c @@ -1054,25 +1054,25 @@ int __video_register_device(struct video_device *vd= ev, vdev->dev.class =3D &video_class; vdev->dev.devt =3D MKDEV(VIDEO_MAJOR, vdev->minor); vdev->dev.parent =3D vdev->dev_parent; + vdev->dev.release =3D v4l2_device_release; dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num); + + /* Increase v4l2_device refcount*/ + v4l2_device_get(vdev->v4l2_dev); + mutex_lock(&videodev_lock); ret =3D device_register(&vdev->dev); if (ret < 0) { mutex_unlock(&videodev_lock); pr_err("%s: device_register failed\n", __func__); - goto cleanup; + put_device(&vdev->dev); + return ret; } - /* Register the release callback that will be called when the last - reference to the device goes away. */ - vdev->dev.release =3D v4l2_device_release; - + if (nr !=3D -1 && nr !=3D vdev->num && warn_if_nr_in_use) pr_warn("%s: requested %s%d, got %s\n", __func__, name_base, nr, video_device_node_name(vdev)); =20 - /* Increase v4l2_device refcount */ - v4l2_device_get(vdev->v4l2_dev); - /* Part 5: Register the entity. */ ret =3D video_register_media_controller(vdev); =20 --=20 2.25.1