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(2001-b011-7011-1a33-56bb-9418-403f-5fc2.dynamic-ip6.hinet.net. [2001:b011:7011:1a33:56bb:9418:403f:5fc2]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-37df411ddf7sm2422204a91.16.2026.06.25.12.39.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Jun 2026 12:39:44 -0700 (PDT) From: Shih-Sheng Yang To: mchehab@kernel.org Cc: hverkuil+cisco@kernel.org, laurent.pinchart+renesas@ideasonboard.com, kees@kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Shih-Sheng Yang Subject: [PATCH] media: v4l2-dev: fix media controller registration error handling Date: Fri, 26 Jun 2026 03:39:16 +0800 Message-Id: <20260625193916.3562596-1-yshihsheng@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit __video_register_device() registers the media-controller entity and interface after cdev_add() and device_register(). The return value from video_register_media_controller() is currently ignored. If media_devnode_create() fails, vdev->intf_devnode remains NULL, but the video device is still marked as registered and the caller sees a successful registration. A later video_unregister_device() reaches v4l2_device_release(), which calls media_devnode_remove() and dereferences that NULL pointer. If media_create_intf_link() fails, the helper removes vdev->intf_devnode but leaves the stale pointer behind. A later release path may then try to remove it again. Fix this by propagating video_register_media_controller() failures from __video_register_device(). Also make the media-controller cleanup path tolerate partially-created state by clearing vdev->intf_devnode after removal and checking it before release-time removal. Signed-off-by: Shih-Sheng Yang --- drivers/media/v4l2-core/v4l2-dev.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c index 6ce623a1245a..5d2faed002a7 100644 --- a/drivers/media/v4l2-core/v4l2-dev.c +++ b/drivers/media/v4l2-core/v4l2-dev.c @@ -203,7 +203,10 @@ static void v4l2_device_release(struct device *cd) #if defined(CONFIG_MEDIA_CONTROLLER) if (v4l2_dev->mdev && vdev->vfl_dir != VFL_DIR_M2M) { /* Remove interfaces and interface links */ - media_devnode_remove(vdev->intf_devnode); + if (vdev->intf_devnode) { + media_devnode_remove(vdev->intf_devnode); + vdev->intf_devnode = NULL; + } if (vdev->entity.function != MEDIA_ENT_F_UNKNOWN) media_device_unregister_entity(&vdev->entity); } @@ -896,6 +899,7 @@ static int video_register_media_controller(struct video_device *vdev) MEDIA_LNK_FL_IMMUTABLE); if (!link) { media_devnode_remove(vdev->intf_devnode); + vdev->intf_devnode = NULL; media_device_unregister_entity(&vdev->entity); return -ENOMEM; } @@ -1087,6 +1091,11 @@ int __video_register_device(struct video_device *vdev, /* Part 5: Register the entity. */ ret = video_register_media_controller(vdev); + if (ret < 0) { + mutex_unlock(&videodev_lock); + put_device(&vdev->dev); + return ret; + } /* Part 6: Activate this minor. The char device can now be used. */ set_bit(V4L2_FL_REGISTERED, &vdev->flags); -- 2.34.1