[PATCH 5.4 087/348] media: v4l2-core: Avoid the dangling pointer in v4l2_fh_release

From: Greg Kroah-Hartman
Date: Mon Jul 12 2021 - 02:18:47 EST


From: Lv Yunlong <lyl2019@xxxxxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxxxxx>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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;
}
--
2.30.2