drm/omap: handle alloc failures in omap_connector

Handle memory allocation failures in omap_connector to avoid NULL
derefs.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180502091159.7071-5-tomi.valkeinen@ti.com
Reviewed-by: Benoit Parrot <bparrot@ti.com>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>

drivers/gpu/drm/omapdrm/omap_connector.c

@@ -121,6 +121,9 @@ static int omap_connector_get_modes(struct drm_connector *connector)
 	if (dssdrv->read_edid) {
 		void *edid = kzalloc(MAX_EDID, GFP_KERNEL);
 
+		if (!edid)
+			return 0;
+
 		if ((dssdrv->read_edid(dssdev, edid, MAX_EDID) > 0) &&
 				drm_edid_is_valid(edid)) {
 			drm_mode_connector_update_edid_property(
@@ -139,6 +142,9 @@ static int omap_connector_get_modes(struct drm_connector *connector)
 		struct drm_display_mode *mode = drm_mode_create(dev);
 		struct videomode vm = {0};
 
+		if (!mode)
+			return 0;
+
 		dssdrv->get_timings(dssdev, &vm);
 
 		drm_display_mode_from_videomode(&vm, mode);
@@ -200,6 +206,10 @@ static int omap_connector_mode_valid(struct drm_connector *connector,
 	if (!r) {
 		/* check if vrefresh is still valid */
 		new_mode = drm_mode_duplicate(dev, mode);
+
+		if (!new_mode)
+			return MODE_BAD;
+
 		new_mode->clock = vm.pixelclock / 1000;
 		new_mode->vrefresh = 0;
 		if (mode->vrefresh == drm_mode_vrefresh(new_mode))