[PATCH] drm/nouveau: Fix null pointer dereference

[Chenyuan Yang]

The return value of drm_mode_duplicate() is assigned to mode,
which will lead to a NULL pointer dereference on
failure of drm_mode_duplicate(). Add a check to avoid npd.

Signed-off-by: Chenyuan Yang <chenyuan0y at gmail.com>
Fixes: 6ee738610f41 ("drm/nouveau: Add DRM driver for NVIDIA GPUs")
---
 drivers/gpu/drm/nouveau/dispnv04/i2c/ch7006_drv.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv04/i2c/ch7006_drv.c b/drivers/gpu/drm/nouveau/dispnv04/i2c/ch7006_drv.c
index fd2150e07e36..f39a7028933a 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/i2c/ch7006_drv.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/i2c/ch7006_drv.c
@@ -229,6 +229,7 @@ static int ch7006_encoder_get_modes(struct drm_encoder *encoder,
 {
 	struct ch7006_priv *priv = to_ch7006_priv(encoder);
 	const struct ch7006_mode *mode;
+	struct drm_display_mode *drm_mode;
 	int n = 0;
 
 	for (mode = ch7006_modes; mode->mode.clock; mode++) {
@@ -236,9 +237,11 @@ static int ch7006_encoder_get_modes(struct drm_encoder *encoder,
 		    ~mode->valid_norms & 1<<priv->norm)
 			continue;
 
-		drm_mode_probed_add(connector,
-				drm_mode_duplicate(encoder->dev, &mode->mode));
+		drm_mode = drm_mode_duplicate(encoder->dev, &mode->mode);
+		if (!drm_mode)
+			continue;
 
+		drm_mode_probed_add(connector, drm_mode);
 		n++;
 	}
 
-- 
2.34.1