Re: [PATCH 4.5 118/200] [media] videobuf2-v4l2: Verify planes array in buffer dequeueing

Mauro Carvalho Chehab
2016-05-11T16:32:08Z

Hi Greg,

This patch seems to be causing trobles with DVB drivers that uses
videobuf2-dvb.

Just sent a patch reverting it.

Regards,
Mauro

Em Mon, 2 May 2016 17:11:57 -0700
Greg Kroah-Hartman <gregkh@linuxfoundation.org> escreveu:

> 4.5-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Sakari Ailus <sakari.ailus@linux.intel.com>
>
> commit 2c1f6951a8a82e6de0d82b1158b5e493fc6c54ab upstream.
>
> When a buffer is being dequeued using VIDIOC_DQBUF IOCTL, the exact buffer
> which will be dequeued is not known until the buffer has been removed from
> the queue. The number of planes is specific to a buffer, not to the queue.
>
> This does lead to the situation where multi-plane buffers may be requested
> and queued with n planes, but VIDIOC_DQBUF IOCTL may be passed an argument
> struct with fewer planes.
>
> __fill_v4l2_buffer() however uses the number of planes from the dequeued
> videobuf2 buffer, overwriting kernel memory (the m.planes array allocated
> in video_usercopy() in v4l2-ioctl.c) if the user provided fewer
> planes than the dequeued buffer had. Oops!
>
> Fixes: b0e0e1f83de3 ("[media] media: videobuf2: Prepare to divide videobuf2")
>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> ---
> drivers/media/v4l2-core/videobuf2-v4l2.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> --- a/drivers/media/v4l2-core/videobuf2-v4l2.c
> +++ b/drivers/media/v4l2-core/videobuf2-v4l2.c
> @@ -74,6 +74,11 @@ static int __verify_planes_array(struct
> return 0;
> }
>
> +static int __verify_planes_array_core(struct vb2_buffer *vb, const void *pb)
> +{
> + return __verify_planes_array(vb, pb);
> +}
> +
> /**
> * __verify_length() - Verify that the bytesused value for each plane fits in
> * the plane length and that the data offset doesn't exceed the bytesused value.
> @@ -437,6 +442,7 @@ static int __fill_vb2_buffer(struct vb2_
> }
>
> static const struct vb2_buf_ops v4l2_buf_ops = {
> + .verify_planes_array = __verify_planes_array_core,
> .fill_user_buffer = __fill_v4l2_buffer,
> .fill_vb2_buffer = __fill_vb2_buffer,
> .copy_timestamp = __copy_timestamp,
>
>

--
Thanks,
Mauro