linux-kernel - [PATCH RESEND] drm/qxl: fix null pointer dereference in qxl_add

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Message-Id: <20240704140027.304685-1-make24@iscas.ac.cn>
Date: Thu,  4 Jul 2024 22:00:27 +0800
From: Ma Ke <make24@...as.ac.cn>
To: airlied@...hat.com,
	kraxel@...hat.com,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	daniel@...ll.ch,
	noralf@...nnes.org
Cc: virtualization@...ts.linux.dev,
	spice-devel@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Ma Ke <make24@...as.ac.cn>
Subject: [PATCH RESEND] drm/qxl: fix null pointer dereference in qxl_add_mode

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

Fixes: 1b043677d4be ("drm/qxl: add qxl_add_mode helper function")
Signed-off-by: Ma Ke <make24@...as.ac.cn>
---
 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 c6d35c33d5d6..7c11383cd3c4 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 -ENOMEM;
 	if (preferred)
 		mode->type |= DRM_MODE_TYPE_PREFERRED;
 	mode->hdisplay = width;
-- 
2.25.1