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

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Date:	Mon,  2 May 2016 17:11:57 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Hans Verkuil <hans.verkuil@...co.com>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>
Subject: [PATCH 4.5 118/200] [media] videobuf2-v4l2: Verify planes array in buffer dequeueing

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,