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From: "Gustavo A. R. Silva" <garsilva@embeddedor.com>
Date: Fri, 2 Feb 2018 06:42:33 -0600
Subject: drm/msm/dsi: Fix potential NULL pointer dereference in
 msm_dsi_modeset_init
Git-commit: 52749d601a6055da3352842575408fcba6f1da46
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

_dev_ is being dereferenced before it is null checked, hence there
is a potential null pointer dereference.

Fix this by moving the pointer dereference after _dev_ has been
null checked.

Fixes: d4e7f38d70ef ("drm/msm/dsi: check msm_dsi and dsi pointers before use")
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/msm/dsi/dsi.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/msm/dsi/dsi.c
+++ b/drivers/gpu/drm/msm/dsi/dsi.c
@@ -192,13 +192,14 @@ void __exit msm_dsi_unregister(void)
 int msm_dsi_modeset_init(struct msm_dsi *msm_dsi, struct drm_device *dev,
 			 struct drm_encoder *encoder)
 {
-	struct msm_drm_private *priv = dev->dev_private;
+	struct msm_drm_private *priv;
 	struct drm_bridge *ext_bridge;
 	int ret;
 
 	if (WARN_ON(!encoder) || WARN_ON(!msm_dsi) || WARN_ON(!dev))
 		return -EINVAL;
 
+	priv = dev->dev_private;
 	msm_dsi->dev = dev;
 
 	ret = msm_dsi_host_modeset_init(msm_dsi->host, dev);