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[media] v4l: vb2: Fix race condition in _vb2_fop_release

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The function releases the queue if the file being released is the queue
owner. The check reads the queue->owner field without taking the queue
lock, creating a race condition with functions that set the queue owner,
such as vb2_ioctl_reqbufs() for instance.

Fix this by moving the queue->owner check within the mutex protected
section.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This commit is contained in:
Laurent Pinchart 2014-11-01 10:32:28 -03:00 committed by Mauro Carvalho Chehab
parent f6cee18858
commit 69c0e9c547
1 changed files with 4 additions and 4 deletions
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8
drivers/media/v4l2-core/videobuf2-core.c
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@ -3389,14 +3389,14 @@ int _vb2_fop_release(struct file *file, struct mutex *lock)
{
struct video_device *vdev = video_devdata(file);
if (lock)
mutex_lock(lock);
if (file->private_data == vdev->queue->owner) {
if (lock)
mutex_lock(lock);
vb2_queue_release(vdev->queue);
vdev->queue->owner = NULL;
if (lock)
mutex_unlock(lock);
}
if (lock)
mutex_unlock(lock);
return v4l2_fh_release(file);
}
EXPORT_SYMBOL_GPL(_vb2_fop_release);