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

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Date:	Wed, 11 May 2016 13:31:59 -0300
From:	Mauro Carvalho Chehab <mchehab@....samsung.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	<linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Hans Verkuil <hans.verkuil@...co.com>
Subject: Re: [PATCH 4.5 118/200] [media] videobuf2-v4l2: Verify planes array
 in buffer dequeueing

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@...uxfoundation.org> escreveu:

> 4.5-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Sakari Ailus <sakari.ailus@...ux.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@...ux.intel.com>
> Acked-by: Hans Verkuil <hans.verkuil@...co.com>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@....samsung.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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