drm: rcar-du: lvds: Fix crash in .atomic_check when disabling connector

Laurent Pinchart · Laurent Pinchart · commit 643ca198aacc · 2018-05-20T10:16:59.000+03:00
The connector .atomic_check() handler can be called with a NULL crtc pointer in the connector state when the connector gets disabled explicitly (through performing a legacy mode set or setting the connector's CRTC_ID property to 0). This causes a crash as the crtc pointer is dereferenced without any check. Fix it by returning from the .atomic_check() handler when then crtc pointer is NULL, as there is no check to be performed when the connector gets disabled. Fixes: c6a27fa ("drm: rcar-du: Convert LVDS encoder code to bridge driver") Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
@@ -88,6 +88,9 @@ static int rcar_lvds_connector_atomic_check(struct drm_connector *connector,
 	const struct drm_display_mode *panel_mode;
 	struct drm_crtc_state *crtc_state;
 
+	if (!state->crtc)
+		return 0;
+
 	if (list_empty(&connector->modes)) {
 		dev_dbg(lvds->dev, "connector: empty modes list\n");
 		return -EINVAL;
