On 08/06/2013 10:10 PM, Laurent Pinchart wrote:
> The vb2_fop_mmap() and vb2_fop_get_unmapped_area() functions are plug-in
> implementation of the mmap() and get_unmapped_area() file operations
> that calls vb2_mmap() and vb2_get_unmapped_area() on the queue
> associated with the video device. Neither the
> vb2_fop_mmap/vb2_fop_get_unmapped_area nor the
> v4l2_mmap/vb2_get_unmapped_area functions in the V4L2 core take any
> lock, leading to race conditions between mmap/get_unmapped_area and
> other buffer-related ioctls such as VIDIOC_REQBUFS.
>
> Fix it by taking the queue or device lock around the vb2_mmap() and
> vb2_get_unmapped_area() calls.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
Acked-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Thanks!
Hans
> ---
> drivers/media/v4l2-core/videobuf2-core.c | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index 9fc4bab..c9b50c7 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -2578,8 +2578,15 @@ EXPORT_SYMBOL_GPL(vb2_ioctl_expbuf);
> int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma)
> {
> struct video_device *vdev = video_devdata(file);
> + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;
> + int err;
>
> - return vb2_mmap(vdev->queue, vma);
> + if (lock && mutex_lock_interruptible(lock))
> + return -ERESTARTSYS;
> + err = vb2_mmap(vdev->queue, vma);
> + if (lock)
> + mutex_unlock(lock);
> + return err;
> }
> EXPORT_SYMBOL_GPL(vb2_fop_mmap);
>
> @@ -2685,8 +2692,15 @@ unsigned long vb2_fop_get_unmapped_area(struct file *file, unsigned long addr,
> unsigned long len, unsigned long pgoff, unsigned long flags)
> {
> struct video_device *vdev = video_devdata(file);
> + struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;
> + int ret;
>
> - return vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags);
> + if (lock && mutex_lock_interruptible(lock))
> + return -ERESTARTSYS;
> + ret = vb2_get_unmapped_area(vdev->queue, addr, len, pgoff, flags);
> + if (lock)
> + mutex_unlock(lock);
> + return ret;
> }
> EXPORT_SYMBOL_GPL(vb2_fop_get_unmapped_area);
> #endif
>
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