linux-kernel - [PATCH 4.9 038/245] media: v4l2-core: Avoid the dangling pointer in v4l2_fh

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Message-Id: <20210719144941.623497768@linuxfoundation.org>
Date:   Mon, 19 Jul 2021 16:49:40 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lv Yunlong <lyl2019@...l.ustc.edu.cn>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 038/245] media: v4l2-core: Avoid the dangling pointer in v4l2_fh_release

From: Lv Yunlong <lyl2019@...l.ustc.edu.cn>

[ Upstream commit 7dd0c9e547b6924e18712b6b51aa3cba1896ee2c ]

A use after free bug caused by the dangling pointer
filp->privitate_data in v4l2_fh_release.
See https://lore.kernel.org/patchwork/patch/1419058/.

My patch sets the dangling pointer to NULL to provide
robust.

Signed-off-by: Lv Yunlong <lyl2019@...l.ustc.edu.cn>
Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/media/v4l2-core/v4l2-fh.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/media/v4l2-core/v4l2-fh.c b/drivers/media/v4l2-core/v4l2-fh.c
index 0c5e69070586..d44b289205b4 100644
--- a/drivers/media/v4l2-core/v4l2-fh.c
+++ b/drivers/media/v4l2-core/v4l2-fh.c
@@ -109,6 +109,7 @@ int v4l2_fh_release(struct file *filp)
 		v4l2_fh_del(fh);
 		v4l2_fh_exit(fh);
 		kfree(fh);
+		filp->private_data = NULL;
 	}
 	return 0;
 }
-- 
2.30.2