[PATCH 1/3] drm/bridge: imx8qxp-ldb: Fix NULL pointer dereference in imx8qxp_ldb_bridge_destroy()

[Liu Ying]

Pointer bridge->driver_private in imx8qxp_ldb_bridge_destroy() is NULL
when a LDB channel is unavailable or imx8qxp_ldb_probe() returns error,
because ldb_add_bridge_helper() is the last function called from
imx8qxp_ldb_probe() and it doesn't initialize bridge->driver_private if
a LDB channel is unavailable.  The NULL pointer would be set to pointer
ldb_ch and then NULL pointer ldb_ch would be dereferenced.  Fix this
by returning early from imx8qxp_ldb_bridge_destroy() if !ldb_ch is true.

Fixes: 32529d384cea ("drm/bridge: imx8qxp-ldb: convert to of_drm_find_and_get_bridge()")
Signed-off-by: Liu Ying <victor.liu at nxp.com>
---
 drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c b/drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c
index 43b328cb5314..ada11eed13cf 100644
--- a/drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c
+++ b/drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c
@@ -65,9 +65,12 @@ static inline struct imx8qxp_ldb *base_to_imx8qxp_ldb(struct ldb *base)
 static void imx8qxp_ldb_bridge_destroy(struct drm_bridge *bridge)
 {
 	struct ldb_channel *ldb_ch = bridge->driver_private;
-	struct ldb *ldb = ldb_ch->ldb;
-	struct imx8qxp_ldb *imx8qxp_ldb = base_to_imx8qxp_ldb(ldb);
+	struct imx8qxp_ldb *imx8qxp_ldb;
+
+	if (!ldb_ch)
+		return;
 
+	imx8qxp_ldb = base_to_imx8qxp_ldb(ldb_ch->ldb);
 	drm_bridge_put(imx8qxp_ldb->companion);
 }
 

-- 
2.43.0