[PATCH 5.4 155/155] media: v4l2-core: fix a use-after-free bug of sd->devnode

Greg Kroah-Hartman
2020-03-31T09:19:32Z

From: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>

commit 6990570f7e0a6078e11b9c5dc13f4b6e3f49a398 upstream.

sd->devnode is released after calling
v4l2_subdev_release. Therefore it should be set
to NULL so that the subdev won't hold a pointer
to a released object. This fixes a reference
after free bug in function
v4l2_device_unregister_subdev

Fixes: 0e43734d4c46e ("media: v4l2-subdev: add release() internal op")

Cc: stable@vger.kernel.org
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/media/v4l2-core/v4l2-device.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/media/v4l2-core/v4l2-device.c
+++ b/drivers/media/v4l2-core/v4l2-device.c
@@ -179,6 +179,7 @@ static void v4l2_subdev_release(struct v

if (sd->internal_ops && sd->internal_ops->release)
sd->internal_ops->release(sd);
+ sd->devnode = NULL;
module_put(owner);
}