On Fri, Mar 14, 2025 at 11:00:26AM -0500, Chenyuan Yang wrote:
> HI Maxime.
>
> Thanks so much for pointing that out!
>
> How about such a patch?
>
This patch is corrupted so we can't review it.
> diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c
> b/drivers/gpu/drm/sun4i/sun4i_backend.c
> index 2dded3b828df..5ad0e90d3e6b 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_backend.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
> @@ -490,9 +490,14 @@ static int sun4i_backend_atomic_check(struct
> sunxi_engine *engine,
> drm_for_each_plane_mask(plane, drm, crtc_state->plane_mask) {
> struct drm_plane_state *plane_state =
> drm_atomic_get_plane_state(state, plane);
> - struct sun4i_layer_state *layer_state =
> - state_to_sun4i_layer_state(plane_state);
> - struct drm_framebuffer *fb = plane_state->fb;
> + struct sun4i_layer_state *layer_state = NULL;
> + struct drm_framebuffer *fb = NULL;
No need to initialize things like this. NULL isn't a valid pointer.
This just disables static checker tools from finding uninitialized
variable warnings so all the expense of writing the checker tools is
now wasted.
regards,
dan carpenter
> +
> + if (IS_ERR(plane_state))
> + return PTR_ERR(plane_state);
> +
> + layer_state = state_to_sun4i_layer_state(plane_state);
> + fb = plane_state->fb;
>
> if (!sun4i_backend_plane_is_supported(plane_state,
> &layer_state->uses_frontend))
> --
>
> -Chenyuan
>
> On Fri, Mar 14, 2025 at 2:17 AM Maxime Ripard <mrip...@kernel.org> wrote:
> >
> > Hi,
> >
> > On Thu, Mar 13, 2025 at 08:20:29PM -0500, Chenyuan Yang wrote:
> > > The function sun4i_backend_atomic_check was dereferencing pointers
> > > returned by drm_atomic_get_plane_state without checking for errors. This
> > > could lead to undefined behavior if the function returns an error pointer.
> > >
> > > This commit adds checks using IS_ERR to ensure that plane_state is
> > > valid before dereferencing them.
> > >
> > > Similar to commit da29abe71e16
> > > ("drm/amd/display: Fix error pointers in
> > > amdgpu_dm_crtc_mem_type_changed").
> > >
> > > Fixes: 96180dde23b7 ("drm/sun4i: backend: Add a custom atomic_check for
> > > the frontend")
> > > Signed-off-by: Chenyuan Yang <chenyua...@gmail.com>
> > > ---
> > > drivers/gpu/drm/sun4i/sun4i_backend.c | 4 ++++
> > > 1 file changed, 4 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c
> > > b/drivers/gpu/drm/sun4i/sun4i_backend.c
> > > index 2dded3b828df..a8e0e2123764 100644
> > > --- a/drivers/gpu/drm/sun4i/sun4i_backend.c
> > > +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
> > > @@ -490,6 +490,10 @@ static int sun4i_backend_atomic_check(struct
> > > sunxi_engine *engine,
> > > drm_for_each_plane_mask(plane, drm, crtc_state->plane_mask) {
> > > struct drm_plane_state *plane_state =
> > > drm_atomic_get_plane_state(state, plane);
> > > +
> > > + if (IS_ERR(plane_state))
> > > + return PTR_ERR(plane_state);
> > > +
> >
> > This introduces a build warning. You shouldn't mix declarations and code.
> >
> > Maxime
