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@xxxxxxxxxxxxxxx>
---
drivers/media/v4l2-core/videobuf2-v4l2.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/media/v4l2-core/videobuf2-v4l2.c b/drivers/media/v4l2-core/videobuf2-v4l2.c
index 91f5521..8da7470 100644
--- 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 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,
--
2.1.4
--
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