HI Maxime. Thanks so much for pointing that out! How about such a patch? 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; + + 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 <mripard@xxxxxxxxxx> 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 <chenyuan0y@xxxxxxxxx> > > --- > > 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