drm/msm/dpu: Add a null ptr check for dpu_encoder_needs_modeset

[PATCH] drm/msm/dpu: Add a null ptr check for dpu_encoder_needs_modeset

Posted by Chenyuan Yang 2 months, 2 weeks ago

The drm_atomic_get_new_connector_state() can return NULL if the
connector is not part of the atomic state. Add a check to prevent
a NULL pointer dereference.

This follows the same pattern used in dpu_encoder_update_topology()
within the same file, which checks for NULL before using conn_state.

Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
Fixes: 1ce69c265a53 ("drm/msm/dpu: move resource allocation to CRTC")
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index c0ed110a7d30..4bddb9504796 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -729,6 +729,8 @@ bool dpu_encoder_needs_modeset(struct drm_encoder *drm_enc, struct drm_atomic_st
 		return false;
 
 	conn_state = drm_atomic_get_new_connector_state(state, connector);
+	if (!conn_state)
+		return false;
 
 	/**
 	 * These checks are duplicated from dpu_encoder_update_topology() since
-- 
2.34.1

Re: [PATCH] drm/msm/dpu: Add a null ptr check for dpu_encoder_needs_modeset

Posted by Dmitry Baryshkov 2 months, 2 weeks ago

On Tue, Jul 22, 2025 at 04:17:40PM -0500, Chenyuan Yang wrote:
> The drm_atomic_get_new_connector_state() can return NULL if the
> connector is not part of the atomic state. Add a check to prevent
> a NULL pointer dereference.
> 
> This follows the same pattern used in dpu_encoder_update_topology()
> within the same file, which checks for NULL before using conn_state.
> 
> Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
> Fixes: 1ce69c265a53 ("drm/msm/dpu: move resource allocation to CRTC")
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index c0ed110a7d30..4bddb9504796 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -729,6 +729,8 @@ bool dpu_encoder_needs_modeset(struct drm_encoder *drm_enc, struct drm_atomic_st
>  		return false;
>  
>  	conn_state = drm_atomic_get_new_connector_state(state, connector);
> +	if (!conn_state)
> +		return false;

Did this happen in a real case or is it just
yet-another-static-analysys?

>  
>  	/**
>  	 * These checks are duplicated from dpu_encoder_update_topology() since
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry

Re: [PATCH] drm/msm/dpu: Add a null ptr check for dpu_encoder_needs_modeset

Posted by Chenyuan Yang 2 months, 2 weeks ago

On Wed, Jul 23, 2025 at 12:05 PM Dmitry Baryshkov
<dmitry.baryshkov@oss.qualcomm.com> wrote:
>
> On Tue, Jul 22, 2025 at 04:17:40PM -0500, Chenyuan Yang wrote:
> > The drm_atomic_get_new_connector_state() can return NULL if the
> > connector is not part of the atomic state. Add a check to prevent
> > a NULL pointer dereference.
> >
> > This follows the same pattern used in dpu_encoder_update_topology()
> > within the same file, which checks for NULL before using conn_state.
> >
> > Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
> > Fixes: 1ce69c265a53 ("drm/msm/dpu: move resource allocation to CRTC")
> > ---
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > index c0ed110a7d30..4bddb9504796 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > @@ -729,6 +729,8 @@ bool dpu_encoder_needs_modeset(struct drm_encoder *drm_enc, struct drm_atomic_st
> >               return false;
> >
> >       conn_state = drm_atomic_get_new_connector_state(state, connector);
> > +     if (!conn_state)
> > +             return false;
>
> Did this happen in a real case or is it just
> yet-another-static-analysys?

This is a static-analysis detected bug.

> >
> >       /**
> >        * These checks are duplicated from dpu_encoder_update_topology() since
> > --
> > 2.34.1
> >
>
> --
> With best wishes
> Dmitry

Re: [PATCH] drm/msm/dpu: Add a null ptr check for dpu_encoder_needs_modeset

Posted by Dmitry Baryshkov 1 month, 3 weeks ago

On Wed, Jul 23, 2025 at 12:43:06PM -0700, Chenyuan Yang wrote:
> On Wed, Jul 23, 2025 at 12:05 PM Dmitry Baryshkov
> <dmitry.baryshkov@oss.qualcomm.com> wrote:
> >
> > On Tue, Jul 22, 2025 at 04:17:40PM -0500, Chenyuan Yang wrote:
> > > The drm_atomic_get_new_connector_state() can return NULL if the
> > > connector is not part of the atomic state. Add a check to prevent
> > > a NULL pointer dereference.
> > >
> > > This follows the same pattern used in dpu_encoder_update_topology()
> > > within the same file, which checks for NULL before using conn_state.
> > >
> > > Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
> > > Fixes: 1ce69c265a53 ("drm/msm/dpu: move resource allocation to CRTC")
> > > ---
> > >  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > index c0ed110a7d30..4bddb9504796 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > @@ -729,6 +729,8 @@ bool dpu_encoder_needs_modeset(struct drm_encoder *drm_enc, struct drm_atomic_st
> > >               return false;
> > >
> > >       conn_state = drm_atomic_get_new_connector_state(state, connector);
> > > +     if (!conn_state)
> > > +             return false;
> >
> > Did this happen in a real case or is it just
> > yet-another-static-analysys?
> 
> This is a static-analysis detected bug.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>



> 
> > >
> > >       /**
> > >        * These checks are duplicated from dpu_encoder_update_topology() since
> > > --
> > > 2.34.1
> > >
> >
> > --
> > With best wishes
> > Dmitry

-- 
With best wishes
Dmitry