Hi Sakari,
Thank you for the patch.
On Thursday, 13 December 2018 12:40:04 EET Sakari Ailus wrote:
> PAGE_ALIGN() may wrap the buffer size around to 0. Prevent this by
> checking that the aligned value is not smaller than the unaligned one.
>
> Note on backporting to stable: the file used to be under
> drivers/media/v4l2-core, it was moved to the current location after 4.14.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> drivers/media/common/videobuf2/videobuf2-core.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c
> b/drivers/media/common/videobuf2/videobuf2-core.c index
> 0ca81d495bdaf..0234ddbfa4de2 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -207,6 +207,10 @@ static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
> for (plane = 0; plane < vb->num_planes; ++plane) {
> unsigned long size = PAGE_ALIGN(vb->planes[plane].length);
>
> + /* Did it wrap around? */
> + if (size < vb->planes[plane].length)
> + goto free;
> +
> mem_priv = call_ptr_memop(vb, alloc,
> q->alloc_devs[plane] ? : q->dev,
> q->dma_attrs, size, q->dma_dir, q->gfp_flags);
Wouldn't it be better to reject length > INT_MAX (or some variations of that)
a few steps before, for instance just before calling __vb2_queue_alloc() ?
There's already a check in vb2_core_reqbufs():
/* Check that driver has set sane values */
if (WARN_ON(!num_planes))
return -EINVAL;
for (i = 0; i < num_planes; i++)
if (WARN_ON(!plane_sizes[i]))
return -EINVAL;
It could be extended to validate the sizes against wrap-around, and moved to a
separate function to be called in vb2_core_create_bufs() as well (as those
checks are missing there). Alternatively, the checks could be moved to the
beginning of __vb2_queue_alloc().
--
Regards,
Laurent Pinchart
