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

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Date:   Sun,  9 May 2021 01:24:02 -0700
From:   Lv Yunlong <lyl2019@...l.ustc.edu.cn>
To:     mchehab@...nel.org, s.nawrocki@...sung.com
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lv Yunlong <lyl2019@...l.ustc.edu.cn>
Subject: [PATCH] media:v4l2-core: Avoid the dangling pointer in v4l2_fh_release

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>
---
 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 684574f58e82..90eec79ee995 100644
--- a/drivers/media/v4l2-core/v4l2-fh.c
+++ b/drivers/media/v4l2-core/v4l2-fh.c
@@ -96,6 +96,7 @@ int v4l2_fh_release(struct file *filp)
 		v4l2_fh_del(fh);
 		v4l2_fh_exit(fh);
 		kfree(fh);
+		filp->private_data = NULL;
 	}
 	return 0;
 }
-- 
2.25.1