linux-kernel - [PATCH] drm/i2c/ch7006: fix a possible null pointer dereference

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Date:   Sat,  7 Oct 2023 11:17:12 +0800
From:   Ma Ke <make_ruc2021@....com>
To:     airlied@...il.com, daniel@...ll.ch, javierm@...hat.com,
        lyude@...hat.com, mripard@...nel.org,
        u.kleine-koenig@...gutronix.de, noralf@...nnes.org,
        tzimmermann@...e.de, make_ruc2021@....com
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH] drm/i2c/ch7006: fix a possible null pointer dereference

In ch7006_encoder_get_modes(), 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: Ma Ke <make_ruc2021@....com>
---
 drivers/gpu/drm/i2c/ch7006_drv.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i2c/ch7006_drv.c b/drivers/gpu/drm/i2c/ch7006_drv.c
index 131512a5f3bd..27c2f02f5b43 100644
--- a/drivers/gpu/drm/i2c/ch7006_drv.c
+++ b/drivers/gpu/drm/i2c/ch7006_drv.c
@@ -236,8 +236,10 @@ 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));
+		struct drm_display_mode *encoder_mode;
+		encoder_mode = drm_mode_duplicate(encoder->dev, &mode->mode);
+		if (!mode)
+			continue;
 
 		n++;
 	}
-- 
2.37.2