[PATCH] drm/amd/display: fix null pointer deref error

[Alex Deucher]

On Tue, Jun 7, 2022 at 1:40 PM Rodrigo Siqueira Jordao
<Rodrigo.Siqueira at amd.com> wrote:
>
>
>
> On 2022-06-07 13:06, Aurabindo Pillai wrote:
> > [Why]
> > 0 was passed in place of a pointer which triggered null pointer
> > dereference.
> >
> > [How]
> > Pass in a pointer that contains nullified parameters instead of null
> > pointer.
> >
> > Signed-off-by: Aurabindo Pillai <aurabindo.pillai at amd.com>
> > ---
> >   .../gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c  | 9 ++++++---
> >   1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
> > index 631a8a2f9fc3..e7944c881148 100644
> > --- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
> > +++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
> > @@ -2191,15 +2191,18 @@ static void dce110_setup_audio_dto(
> >                       build_audio_output(context, pipe_ctx, &audio_output);
> >
> >                       if (dc->res_pool->dccg && dc->res_pool->dccg->funcs->set_audio_dtbclk_dto) {
> > -                             /* disable audio DTBCLK DTO */
> > -                             dc->res_pool->dccg->funcs->set_audio_dtbclk_dto(
> > -                                     dc->res_pool->dccg, 0);
> > +                             struct dtbclk_dto_params dto_params = {0};
> >
> >                               pipe_ctx->stream_res.audio->funcs->wall_dto_setup(
> >                                               pipe_ctx->stream_res.audio,
> >                                               pipe_ctx->stream->signal,
> >                                               &audio_output.crtc_info,
> >                                               &audio_output.pll_info);
> > +
> > +                             /* disable audio DTBCLK DTO */
> > +                             dc->res_pool->dccg->funcs->set_audio_dtbclk_dto(
> > +                                     dc->res_pool->dccg, &dto_params);
> > +
> >                       } else
> >                               pipe_ctx->stream_res.audio->funcs->wall_dto_setup(
> >                                       pipe_ctx->stream_res.audio,
>
> Maybe it is a good idea to add the Fixes tag that points to the commit
> that introduced this regression. Anyway, I'm ok with this change.

Or at least explain in what case you might hit it or an example backtrace.

Alex

>
> Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
>