[PATCH 1/8] drm/edid: Check the number of detailed timing descriptors in the CEA ext block

[Ville Syrjälä]

On Tue, Jan 28, 2020 at 05:18:34PM +0100, Daniel Vetter wrote:
> On Tue, Jan 28, 2020 at 5:15 PM Ville Syrjälä
> <ville.syrjala at linux.intel.com> wrote:
> >
> > On Tue, Jan 28, 2020 at 04:17:58PM +0100, Daniel Vetter wrote:
> > > On Fri, Jan 24, 2020 at 10:02:24PM +0200, Ville Syrjala wrote:
> > > > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > >
> > > > CEA-861 says :
> > > > "d = offset for the byte following the reserved data block.
> > > >  If no data is provided in the reserved data block, then d=4.
> > > >  If no DTDs are provided, then d=0."
> > > >
> > > > So let's not look for DTDs when d==0. In fact let's just make that
> > > > <4 since those values would just mean that he DTDs overlap the block
> > > > header. And let's also check that d isn't so big as to declare
> > > > the descriptors to live past the block end, although the code
> > > > does already survive that case as we'd just end up with a negative
> > > > number of descriptors and the loop would not do anything.
> > > >
> > > > Cc: Allen Chen <allen.chen at ite.com.tw>
> > > > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > >
> > > Hm I think edid parsing is like the perfect use-case for some in-kernel
> > > unit tests ... In case anyone feels motivated?
> >
> > Another idea I've been putting off is simply shoving the parser into
> > userspace. Kinda looks like with fork_usermode_blob() we could embed
> > the executable into the kernel/module and thus avoid the problem of
> > actually shipping the binary somehow.
> 
> "How to run unit tests without losing hair" is essentially what kunit
> tries to solve. I think we should cut over to that (it's merged now,
> should be good enough for at least the edid parser, mocking stuff
> isn't there there), and then make sure CI runs that stuff for us. Then
> we could convert over at least the unit test like selftests eventually
> too.

I meant run it in userspace *always*, not just for testing.

-- 
Ville Syrjälä
Intel