On Thu 03-03-16 20:12:48, Ricardo Ribalda Delgado wrote:
> On page unaligned frames, create_framevec forces get_vaddr_frames to
> allocate an extra page at the end of the buffer. Under some
> circumstances, this leads to -EINVAL on VIDIOC_QBUF.
>
> E.g:
> We have vm_a that vm_area that goes from 0x1000 to 0x3000. And a
> frame that goes from 0x1800 to 0x2800, i.e. 2 pages.
>
> frame_vector_create will be called with the following params:
>
> get_vaddr_frames(0x1800 , 2, write, 1, vec);
>
> get_vaddr will allocate the first page after checking that the memory
> 0x1800-0x27ff is valid, but it will not allocate the second page because
> the range 0x2800-0x37ff is out of the vm_a range. This results in
> create_framevec returning -EFAULT
>
> Error Trace:
> [ 9083.793015] video0: VIDIOC_QBUF: 00:00:00.00000000 index=1,
> type=vid-cap, flags=0x00002002, field=any, sequence=0,
> memory=userptr, bytesused=0, offset/userptr=0x7ff2b023ca80, length=5765760
> [ 9083.793028] timecode=00:00:00 type=0, flags=0x00000000,
> frames=0, userbits=0x00000000
> [ 9083.793117] video0: VIDIOC_QBUF: error -22: 00:00:00.00000000
> index=2, type=vid-cap, flags=0x00000000, field=any, sequence=0,
> memory=userptr, bytesused=0, offset/userptr=0x7ff2b07bc500, length=5765760
>
> Fixes: 21fb0cb7ec65 ("[media] vb2: Provide helpers for mapping virtual addresses")
> Reported-by: Albert Antony <albert@xxxxxxxxx>
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@xxxxxxxxx>
The patch looks good. Thanks for fixing this! You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
>
> Maybe we should cc stable.
>
> This error has not pop-out yet because userptr is usually called with memory
> on the heap and malloc usually overallocate. This error has been a pain to trace :).
>
> Regards!
>
>
>
> drivers/media/v4l2-core/videobuf2-memops.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-memops.c b/drivers/media/v4l2-core/videobuf2-memops.c
> index dbec5923fcf0..e4e4976c6849 100644
> --- a/drivers/media/v4l2-core/videobuf2-memops.c
> +++ b/drivers/media/v4l2-core/videobuf2-memops.c
> @@ -49,7 +49,7 @@ struct frame_vector *vb2_create_framevec(unsigned long start,
> vec = frame_vector_create(nr);
> if (!vec)
> return ERR_PTR(-ENOMEM);
> - ret = get_vaddr_frames(start, nr, write, 1, vec);
> + ret = get_vaddr_frames(start & PAGE_MASK, nr, write, 1, vec);
> if (ret < 0)
> goto out_destroy;
> /* We accept only complete set of PFNs */
> --
> 2.7.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
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