Overview
About vulnerability
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:
- After core-1 kfree idev, the core-2 will do use-after-free for idev.
- 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.
Details
- Affected product:
- AlmaLinux 9.2 ESU , CentOS 6 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 6 ELS , CloudLinux 7 ELS , Oracle Linux 6 ELS , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS
- Affected packages:
- kernel @ 2.6.32 (+12 more)
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:
- After core-1 kfree idev, the core-2 will do use-after-free for idev.
- 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.