Vulnerability CVE-2023-52439
Published: 2024-02-20

Description:
In the Linux kernel, the following vulnerability has been resolved:

uio: Fix use-after-free in uio_open

core-1 core-2
-------------------------------------------------------
uio_unregister_device uio_open
idev = idr_find()
device_unregister(&idev->dev)
put_device(&idev->dev)
uio_device_release
get_device(&idev->dev)
kfree(idev)
uio_free_minor(minor)
uio_release
put_device(&idev->dev)
kfree(idev)
-------------------------------------------------------

In the core-1 uio_unregister_device(), the device_unregister will kfree
idev when the idev->dev kobject ref is 1. But after core-1
device_unregister, put_device and before doing kfree, the core-2 may
get_device. Then:
1. After core-1 kfree idev, the core-2 will do use-after-free for idev.
2. When core-2 do uio_release and put_device, the idev will be double
freed.

To address this issue, we can get idev atomic & inc idev reference with
minor_lock.

 References:
https://git.kernel.org/stable/c/3174e0f7de1ba392dc191625da83df02d695b60c
https://git.kernel.org/stable/c/e93da893d52d82d57fc0db2ca566024e0f26ff50
https://git.kernel.org/stable/c/5e0be1229ae199ebb90b33102f74a0f22d152570
https://git.kernel.org/stable/c/5cf604ee538ed0c467abe3b4cda5308a6398f0f7
https://git.kernel.org/stable/c/17a8519cb359c3b483fb5c7367efa9a8a508bdea
https://git.kernel.org/stable/c/35f102607054faafe78d2a6994b18d5d9d6e92ad
https://git.kernel.org/stable/c/913205930da6213305616ac539447702eaa85e41
https://git.kernel.org/stable/c/0c9ae0b8605078eafc3bea053cc78791e97ba2e2
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