[PATCH] drm/qxl: fix a possible null pointer dereference

[Ma Ke]

In qxl_add_mode(), the return value of drm_cvt_mode() is assigned
to mode, which will lead to a NULL pointer dereference on failure
of drm_cvt_mode(). Add a check to avoid null pointer dereference.

Signed-off-by: Ma Ke <make_ruc2...@163.com>
---
 drivers/gpu/drm/qxl/qxl_display.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/qxl/qxl_display.c 
b/drivers/gpu/drm/qxl/qxl_display.c
index 6492a70e3c39..8a14edaa4aa3 100644
--- a/drivers/gpu/drm/qxl/qxl_display.c
+++ b/drivers/gpu/drm/qxl/qxl_display.c
@@ -236,6 +236,8 @@ static int qxl_add_mode(struct drm_connector *connector,
                return 0;
 
        mode = drm_cvt_mode(dev, width, height, 60, false, false, false);
+       if (!mode)
+               return 0;
        if (preferred)
                mode->type |= DRM_MODE_TYPE_PREFERRED;
        mode->hdisplay = width;
-- 
2.37.2