CVE-2023-52439

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

uio: Fix use-after-free in uio_open

core-1 core-2

uiounregisterdevice uioopen idev = idrfind() deviceunregister(&idev->dev) putdevice(&idev->dev) uiodevicerelease getdevice(&idev->dev) kfree(idev) uiofreeminor(minor) uiorelease put_device(&idev->dev)

kfree(idev)

In the core-1 uiounregisterdevice(), the deviceunregister will kfree idev when the idev->dev kobject ref is 1. But after core-1 deviceunregister, putdevice and before doing kfree, the core-2 may getdevice. Then: 1. After core-1 kfree idev, the core-2 will do use-after-free for idev. 2. When core-2 do uiorelease and putdevice, the idev will be double freed.

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