Re: [PATCH] drm/msm: Fix return type of mdp4_lvds_connector_mode_valid

[Abhinav Kumar]

On 10/31/2022 5:24 PM, Dmitry Baryshkov wrote:
> On 01/11/2022 01:10, Nathan Chancellor wrote:
> > On Tue, Sep 13, 2022 at 01:55:48PM -0700, Nathan Huckleberry wrote:
> > > The mode_valid field in drm_connector_helper_funcs is expected to be of
> > > type:
> > > enum drm_mode_status (* mode_valid) (struct drm_connector *connector,
> > >                                       struct drm_display_mode *mode);
> > >
> > > The mismatched return type breaks forward edge kCFI since the underlying
> > > function definition does not match the function hook definition.
> > >
> > > The return type of mdp4_lvds_connector_mode_valid should be changed from
> > > int to enum drm_mode_status.
> > >
> > > Reported-by: Dan Carpenter <error27@xxxxxxxxx>
> > > Link: https://github.com/ClangBuiltLinux/linux/issues/1703
> > > Cc: llvm@xxxxxxxxxxxxxxx
> > > Signed-off-by: Nathan Huckleberry <nhuck@xxxxxxxxxx>
> > > ---
> > >   drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c | 5 +++--
> > >   1 file changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c 
> > > b/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c
> > > index 7288041dd86a..7444b75c4215 100644
> > > --- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c
> > > +++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c
> > > @@ -56,8 +56,9 @@ static int mdp4_lvds_connector_get_modes(struct 
> > > drm_connector *connector)
> > >       return ret;
> > >   }
> > > -static int mdp4_lvds_connector_mode_valid(struct drm_connector 
> > > *connector,
> > > -                 struct drm_display_mode *mode)
> > > +static enum drm_mode_status
> > > +mdp4_lvds_connector_mode_valid(struct drm_connector *connector,
> > > +                   struct drm_display_mode *mode)
> > >   {
> > >       struct mdp4_lvds_connector *mdp4_lvds_connector =
> > >               to_mdp4_lvds_connector(connector);
> > > --
> > > 2.37.2.789.g6183377224-goog
> >
> > Did this patch get lost somewhere? I do not see it picked up. It is
> > needed to avoid a new WIP warning from clang for catching these CFI
> > failures:
> >
> > drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c:89:16: error: 
> > incompatible function pointer types initializing 'enum drm_mode_status 
> > (*)(struct drm_connector *, struct drm_display_mode *)' with an 
> > expression of type 'int (struct drm_connector *, struct 
> > drm_display_mode *)' 
> > [-Werror,-Wincompatible-function-pointer-types-strict]
> >          .mode_valid = mdp4_lvds_connector_mode_valid,
> >                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > 1 error generated.
>
> It will be picked into 6.1-rc and then propagate through the stable 
> kernel updates.
>
> Anyway:
>
> Fixes: 3e87599b68e7 ("drm/msm/mdp4: add LVDS panel support")
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>

Yes, it was already merged to the -fixes tree and a PR with it was sent 
out for 6.1-rc

https://gitlab.freedesktop.org/drm/msm/-/commit/0b33a33bd15d5bab73b87152b220a8d0153a4587

>