Commit 83934b75 authored Apr 03, 2016 by Sakari Ailus Committed by Mauro Carvalho Chehab Jun 16, 2016

[media] videobuf2-v4l2: Verify planes array in buffer dequeueing



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: b0e0e1f8 ("[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>
Cc: stable@vger.kernel.org # for v4.4 and later
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

parent 126f4029

drivers/media/v4l2-core/videobuf2-v4l2.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -74,6 +74,11 @@ static int __verify_planes_array(struct vb2_buffer *vb, const struct v4l2_buffer
		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_buffer *vb,
		}

		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,