On Thu, Jan 10, 2019 at 02:02:14PM +0100, Hans Verkuil wrote:
> 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.
Even G_FMT? I'm not saying no though. There's just a slight chance of
breaking something as it hasn't been a problem to call G_FMT with incorrect
number of planes in the mplane format; the number would be overwritten
anyway.
Apart from that, this leaves just the four locations --- putting this to a
separate function will reduce the calls to that function to just two.
>
> 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);
> >
>
--
Sakari Ailus
sakari.ailus@xxxxxxxxxxxxxxx
