drm/atomic: Clear crtcs, connectors and planes when clearing state

Users of the atomic state assume that if the pointer to a crtc, plane or
connector is not NULL in the respective object vector, than the state
for that object in *_states vector also won't be NULL. That assumption
was broken by drm_atomic_state_clear(), which would clear the state
pointer but leave the pointer to the object still set.

This fixes a NULL pointer dereference in i915 caused by the use of
drm_atomic_state_clear().

Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 5d3abe3..00ea881 100644 (file)
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -134,6 +134,7 @@ void drm_atomic_state_clear(struct drm_atomic_state *state)
 
                connector->funcs->atomic_destroy_state(connector,
                                                       state->connector_states[i]);
+               state->connectors[i] = NULL;
                state->connector_states[i] = NULL;
        }
 
@@ -145,6 +146,7 @@ void drm_atomic_state_clear(struct drm_atomic_state *state)
 
                crtc->funcs->atomic_destroy_state(crtc,
                                                  state->crtc_states[i]);
+               state->crtcs[i] = NULL;
                state->crtc_states[i] = NULL;
        }
 
@@ -156,6 +158,7 @@ void drm_atomic_state_clear(struct drm_atomic_state *state)
 
                plane->funcs->atomic_destroy_state(plane,
                                                   state->plane_states[i]);
+               state->planes[i] = NULL;
                state->plane_states[i] = NULL;
        }
 }