vc4_plane_atomic_async_update() calls vc4_plane_atomic_check() which in turn calls vc4_plane_setup_clipping_and_scaling(), and since commit 58a6a36fe8e0 ("drm/vc4: Use drm_atomic_helper_check_plane_state() to simplify the logic"), this function accesses plane_state->state which will be NULL when called from the async update path since we're passing previous plane state, and plane_state->state has been assigned to NULL in drm_atomic_helper_swap_state().
Assign plane->state->state to new_plane_state->state before calling vc4_plane_atomic_check() and reset it to NULL after vc4_plane_atomic_check() as returned.
Fixes: 58a6a36fe8e0 ("drm/vc4: Use drm_atomic_helper_check_plane_state() to simplify the logic") Signed-off-by: Boris Brezillon boris.brezillon@bootlin.com --- drivers/gpu/drm/vc4/vc4_plane.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c index 9dc3fcbd290b..c33c7dc2119d 100644 --- a/drivers/gpu/drm/vc4/vc4_plane.c +++ b/drivers/gpu/drm/vc4/vc4_plane.c @@ -827,8 +827,13 @@ static void vc4_plane_atomic_async_update(struct drm_plane *plane, plane->state->src_x = state->src_x; plane->state->src_y = state->src_y;
- /* Update the display list based on the new crtc_x/y. */ + /* Update the display list based on the new crtc_x/y. + * The plane->state->state update dance is needed to avoid NULL pointer + * dereference in vc4_plane_setup_clipping_and_scaling(). + */ + plane->state->state = state->state; vc4_plane_atomic_check(plane, plane->state); + plane->state->state = NULL;
/* Note that we can't just call vc4_plane_write_dlist() * because that would smash the context data that the HVS is