On Sat, Jan 12, 2019 at 10:17:47AM +0100, Hans Verkuil wrote:
> On 1/11/19 10:10 PM, Sakari Ailus wrote:
> > Hi Hans,
> > 
> > On Fri, Jan 11, 2019 at 09:31:25AM +0100, Hans Verkuil wrote:
> >> Three fixes for a bug introduced in 5.0.
> >>
> >> The last patch (Validate num_planes for debug messages) is also backported
> >> to kernels >= 4.12 (the oldest kernel for which it applies cleanly).
> > 
> > The surrounding lines of code have changed slightly over the years. The
> > older kernels still suffer from the same problem as far as I see, so the
> > backport is relevant down to 3.16 at least (but older kernels aren't
> > supported anyway so I didn't check further). The problem was likely
> > introduced by the big IOCTL handling patches long, long time ago. Huh.
> > 
> 
> I didn't plan on backporting this to older kernels. You have to be root
> to enable this debugging, so it is not security bug.

It is a security problem, even if root would have to enable the feature.

In practice it is not that severe as few would end up doing that. But we
don't know. I think it'd be easier to fix it than informing potential users
about its dangers.

I can submit a patch for the older kernels, too.

-- 
Sakari Ailus
sakari.ai...@linux.intel.com

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