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authorHans Verkuil <hverkuil-cisco@xs4all.nl>2024-02-23 11:45:36 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2024-06-16 14:41:35 +0300
commit7170d0c0da31931e90bdb34ed24101582bdc7b2f (patch)
tree0a4b921a13f09bbcd46b6f6c02e62138ef4b8663 /drivers/media
parent5d931a26949b5b35deb740d229db84da180766b1 (diff)
downloadlinux-7170d0c0da31931e90bdb34ed24101582bdc7b2f.tar.xz
media: v4l2-core: hold videodev_lock until dev reg, finishes
commit 1ed4477f2ea4743e7c5e1f9f3722152d14e6eeb1 upstream. After the new V4L2 device node was registered, some additional initialization was done before the device node was marked as 'registered'. During the time between creating the device node and marking it as 'registered' it was possible to open the device node, which would return -ENODEV since the 'registered' flag was not yet set. Hold the videodev_lock mutex from just before the device node is registered until the 'registered' flag is set. Since v4l2_open will take the same lock, it will wait until this registration process is finished. This resolves this race condition. Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com> Cc: <stable@vger.kernel.org> # for vi4.18 and up Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/media')
-rw-r--r--drivers/media/v4l2-core/v4l2-dev.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index 397d553177fa..e73c749c99bd 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -1033,8 +1033,10 @@ int __video_register_device(struct video_device *vdev,
vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
vdev->dev.parent = vdev->dev_parent;
dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
+ mutex_lock(&videodev_lock);
ret = device_register(&vdev->dev);
if (ret < 0) {
+ mutex_unlock(&videodev_lock);
pr_err("%s: device_register failed\n", __func__);
goto cleanup;
}
@@ -1054,6 +1056,7 @@ int __video_register_device(struct video_device *vdev,
/* Part 6: Activate this minor. The char device can now be used. */
set_bit(V4L2_FL_REGISTERED, &vdev->flags);
+ mutex_unlock(&videodev_lock);
return 0;