[PATCH] drm/i915/display: Initalizalize capability variables

[Borah, Chaitanya Kumar]

> -----Original Message-----
> From: Kandpal, Suraj <suraj.kandpal at intel.com>
> Sent: Wednesday, March 27, 2024 9:06 AM
> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>; intel-
> gfx at lists.freedesktop.org
> Subject: RE: [PATCH] drm/i915/display: Initalizalize capability variables
> 
> > Hello Suraj,
> >
> > > -----Original Message-----
> > > From: Kandpal, Suraj <suraj.kandpal at intel.com>
> > > Sent: Tuesday, March 26, 2024 10:45 AM
> > > To: intel-gfx at lists.freedesktop.org
> > > Cc: Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>;
> > > Kandpal, Suraj <suraj.kandpal at intel.com>
> > > Subject: [PATCH] drm/i915/display: Initalizalize capability
> > > variables
> >
> > Typo: Initialize
> >
> 
> Sure will fix
> 
> > > Initialize HDCP capability variables to false to avoid UBSAN warning
> > > in boolean value.
> > >
> >
> > I can see a case where hdcp_cap remains unassigned in case
> > intel_dp_hdcp_get_remote_capability() returns without assigning it a value.
> >
> > Is that intended/expected?
> >
> 
> That is not intentional but this patch makes sure hdcp_capable will be false
> when this function gets called.
> 

This patch makes sense for sure but what I am getting at is if UBSAN is revealing a bug in our code.

intel_dp_hdcp_get_remote_capability() returns if _intel_dp_hdcp2_get_capability() fails. In that case we never check for hdcp 1.4 capability.
If a remote sink can be hdcp 1.4 capable but not hdcp 2 capable, this logic is problematic.

Regards

Chaitanya

> Regards,
> Suraj Kandpal
> 
> > Regards
> >
> > Chaitanya
> >
> > > Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_display_debugfs.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > > b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > > index b99c024b0934..95d14dab089e 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > > @@ -191,7 +191,7 @@ static void intel_hdcp_info(struct seq_file *m,
> > >  			    struct intel_connector *intel_connector,
> > >  			    bool remote_req)
> > >  {
> > > -	bool hdcp_cap, hdcp2_cap;
> > > +	bool hdcp_cap = false, hdcp2_cap = false;
> > >
> > >  	if (!intel_connector->hdcp.shim) {
> > >  		seq_puts(m, "No Connector Support");
> > > --
> > > 2.43.2