drm: panel-lvds: Potential Oops in probe error handling

[ Upstream commit fb2ee9bf084bcaeff1e5be100decc0eacb4af2d5 ]

The "lvds->backlight" pointer could be NULL in situations where
of_parse_phandle() returns NULL.  This code is cleaner if we use the
managed devm_of_find_backlight() so the clean up is automatic.

Fixes: 7c9dff5bd643 ("drm: panels: Add LVDS panel driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190911104928.GA15930@mwanda
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/panel/panel-lvds.c b/drivers/gpu/drm/panel/panel-lvds.c
index ad47cc9..bf5fcc3 100644 (file)
--- a/drivers/gpu/drm/panel/panel-lvds.c
+++ b/drivers/gpu/drm/panel/panel-lvds.c
@@ -197,7 +197,6 @@ static int panel_lvds_parse_dt(struct panel_lvds *lvds)
 static int panel_lvds_probe(struct platform_device *pdev)
 {
        struct panel_lvds *lvds;
-       struct device_node *np;
        int ret;
 
        lvds = devm_kzalloc(&pdev->dev, sizeof(*lvds), GFP_KERNEL);
@@ -243,14 +242,9 @@ static int panel_lvds_probe(struct platform_device *pdev)
                return ret;
        }
 
-       np = of_parse_phandle(lvds->dev->of_node, "backlight", 0);
-       if (np) {
-               lvds->backlight = of_find_backlight_by_node(np);
-               of_node_put(np);
-
-               if (!lvds->backlight)
-                       return -EPROBE_DEFER;
-       }
+       lvds->backlight = devm_of_find_backlight(lvds->dev);
+       if (IS_ERR(lvds->backlight))
+               return PTR_ERR(lvds->backlight);
 
        /*
         * TODO: Handle all power supplies specified in the DT node in a generic
@@ -266,14 +260,10 @@ static int panel_lvds_probe(struct platform_device *pdev)
 
        ret = drm_panel_add(&lvds->panel);
        if (ret < 0)
-               goto error;
+               return ret;
 
        dev_set_drvdata(lvds->dev, lvds);
        return 0;
-
-error:
-       put_device(&lvds->backlight->dev);
-       return ret;
 }
 
 static int panel_lvds_remove(struct platform_device *pdev)
@@ -284,9 +274,6 @@ static int panel_lvds_remove(struct platform_device *pdev)
 
        panel_lvds_disable(&lvds->panel);
 
-       if (lvds->backlight)
-               put_device(&lvds->backlight->dev);
-
        return 0;
 }