[PATCH 4.19 007/106] drm/panel: check failure cases in the probe func

[Greg Kroah-Hartman]

From: Navid Emamdoost <navid.emamdoost@xxxxxxxxx>

[ Upstream commit afd6d4f5a52c16e1483328ac074abb1cde92c29f ]

The following function calls may fail and return NULL, so the null check
is added.
of_graph_get_next_endpoint
of_graph_get_remote_port_parent
of_graph_get_remote_port

Update: Thanks to Sam Ravnborg, for suggession on the use of goto to avoid
leaking endpoint.

Signed-off-by: Navid Emamdoost <navid.emamdoost@xxxxxxxxx>
Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20190724195534.9303-1-navid.emamdoost@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 .../gpu/drm/panel/panel-raspberrypi-touchscreen.c   | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
index 2c9c9722734f5..9a2cb8aeab3a4 100644
--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -400,7 +400,13 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
 
 	/* Look up the DSI host.  It needs to probe before we do. */
 	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
+	if (!endpoint)
+		return -ENODEV;
+
 	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
+	if (!dsi_host_node)
+		goto error;
+
 	host = of_find_mipi_dsi_host_by_node(dsi_host_node);
 	of_node_put(dsi_host_node);
 	if (!host) {
@@ -409,6 +415,9 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
 	}
 
 	info.node = of_graph_get_remote_port(endpoint);
+	if (!info.node)
+		goto error;
+
 	of_node_put(endpoint);
 
 	ts->dsi = mipi_dsi_device_register_full(host, &info);
@@ -429,6 +438,10 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
 		return ret;
 
 	return 0;
+
+error:
+	of_node_put(endpoint);
+	return -ENODEV;
 }
 
 static int rpi_touchscreen_remove(struct i2c_client *i2c)
-- 
2.20.1