On 01/10/19 13:43, Sakari Ailus wrote:
> The for loop to reset the memory of the plane reserved fields runs over
> num_planes provided by the user without validating it. Ensure num_planes
> is no more than VIDEO_MAX_PLANES before the loop.
>
> Fixes: 4e1e0eb0e074 ("media: v4l2-ioctl: Zero v4l2_plane_pix_format reserved fields")
> Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> ---
> Hi folks,
>
> This patch goes on top of Thierry's patch "media: v4l2-ioctl: Clear only
> per-plane reserved fields".
>
> drivers/media/v4l2-core/v4l2-ioctl.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index 392f1228af7b5..9e68a608ac6d3 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -1551,6 +1551,8 @@ static int v4l_s_fmt(const struct v4l2_ioctl_ops *ops,
> if (unlikely(!ops->vidioc_s_fmt_vid_cap_mplane))
> break;
> CLEAR_AFTER_FIELD(p, fmt.pix_mp.xfer_func);
> + if (p->fmt.pix_mp.num_planes > VIDEO_MAX_PLANES)
> + break;
I would check this not here but in check_fmt: all *_FMT ioctls call that function
first, so it makes sense to do the check there.
v4l_print_format should also be adjusted (take the minimum of num_planes and
VIDEO_MAX_PLANES), since it can still be called even if check_fmt returns an
error if num_planes is too large.
In fact, the change to v4l_print_format should be a separate patch since that
should be backported. It can leak memory in the kernel log if num_planes is
too large.
Regards,
Hans
> for (i = 0; i < p->fmt.pix_mp.num_planes; i++)
> CLEAR_AFTER_FIELD(&p->fmt.pix_mp.plane_fmt[i], bytesperline);
> return ops->vidioc_s_fmt_vid_cap_mplane(file, fh, arg);
> @@ -1581,6 +1583,8 @@ static int v4l_s_fmt(const struct v4l2_ioctl_ops *ops,
> if (unlikely(!ops->vidioc_s_fmt_vid_out_mplane))
> break;
> CLEAR_AFTER_FIELD(p, fmt.pix_mp.xfer_func);
> + if (p->fmt.pix_mp.num_planes > VIDEO_MAX_PLANES)
> + break;
> for (i = 0; i < p->fmt.pix_mp.num_planes; i++)
> CLEAR_AFTER_FIELD(&p->fmt.pix_mp.plane_fmt[i], bytesperline);
> return ops->vidioc_s_fmt_vid_out_mplane(file, fh, arg);
> @@ -1648,6 +1652,8 @@ static int v4l_try_fmt(const struct v4l2_ioctl_ops *ops,
> if (unlikely(!ops->vidioc_try_fmt_vid_cap_mplane))
> break;
> CLEAR_AFTER_FIELD(p, fmt.pix_mp.xfer_func);
> + if (p->fmt.pix_mp.num_planes > VIDEO_MAX_PLANES)
> + break;
> for (i = 0; i < p->fmt.pix_mp.num_planes; i++)
> CLEAR_AFTER_FIELD(&p->fmt.pix_mp.plane_fmt[i], bytesperline);
> return ops->vidioc_try_fmt_vid_cap_mplane(file, fh, arg);
> @@ -1678,6 +1684,8 @@ static int v4l_try_fmt(const struct v4l2_ioctl_ops *ops,
> if (unlikely(!ops->vidioc_try_fmt_vid_out_mplane))
> break;
> CLEAR_AFTER_FIELD(p, fmt.pix_mp.xfer_func);
> + if (p->fmt.pix_mp.num_planes > VIDEO_MAX_PLANES)
> + break;
> for (i = 0; i < p->fmt.pix_mp.num_planes; i++)
> CLEAR_AFTER_FIELD(&p->fmt.pix_mp.plane_fmt[i], bytesperline);
> return ops->vidioc_try_fmt_vid_out_mplane(file, fh, arg);
>
