linux-kernel - [PATCH] gpu: lontium-lt9611: Fix NULL pointer dereference in lt9611_connector

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Date:   Wed, 27 Jul 2022 15:31:19 +0800
From:   Zeng Jingxiang <zengjx95@...il.com>
To:     andrzej.hajda@...el.com, narmstrong@...libre.com,
        robert.foss@...aro.org, Laurent.pinchart@...asonboard.com,
        jonas@...boo.se, jernej.skrabec@...il.com, airlied@...ux.ie,
        daniel@...ll.ch
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Zeng Jingxiang <linuszeng@...cent.com>
Subject: [PATCH] gpu: lontium-lt9611: Fix NULL pointer dereference in lt9611_connector_init()

From: Zeng Jingxiang <linuszeng@...cent.com>

A NULL check for bridge->encoder shows that it may be NULL, but it
already been dereferenced on all paths leading to the check.
812	if (!bridge->encoder) {

Dereference the pointer bridge->encoder.
810	drm_connector_attach_encoder(&lt9611->connector, bridge->encoder);

Signed-off-by: Zeng Jingxiang <linuszeng@...cent.com>
---
 drivers/gpu/drm/bridge/lontium-lt9611.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/lontium-lt9611.c b/drivers/gpu/drm/bridge/lontium-lt9611.c
index 7ef8fe5abc12..81a4751573fa 100644
--- a/drivers/gpu/drm/bridge/lontium-lt9611.c
+++ b/drivers/gpu/drm/bridge/lontium-lt9611.c
@@ -807,13 +807,14 @@ static int lt9611_connector_init(struct drm_bridge *bridge, struct lt9611 *lt961
 
 	drm_connector_helper_add(&lt9611->connector,
 				 &lt9611_bridge_connector_helper_funcs);
-	drm_connector_attach_encoder(&lt9611->connector, bridge->encoder);
 
 	if (!bridge->encoder) {
 		DRM_ERROR("Parent encoder object not found");
 		return -ENODEV;
 	}
 
+	drm_connector_attach_encoder(&lt9611->connector, bridge->encoder);
+
 	return 0;
 }
 
-- 
2.27.0