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

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Date:   Fri, 13 Oct 2023 10:03:50 +0800
From:   Ma Ke <make_ruc2021@....com>
To:     airlied@...hat.com, kraxel@...hat.com, airlied@...il.com,
        daniel@...ll.ch
Cc:     virtualization@...ts.linux-foundation.org,
        spice-devel@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, Ma Ke <make_ruc2021@....com>
Subject: [PATCH] drm/qxl: fix a possible null pointer dereference

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_ruc2021@....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