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USN-5240-1: Linux kernel vulnerability

19 January 2022

The system could be made to crash or run programs as an administrator.




William Liu and Jamie Hill-Daniel discovered that the file system context
functionality in the Linux kernel contained an integer underflow
vulnerability, leading to an out-of-bounds write. A local attacker could
use this to cause a denial of service (system crash) or execute arbitrary

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 21.10
Ubuntu 21.04
Ubuntu 20.04
Ubuntu 18.04

After a standard system update you need to reboot your computer to make
all the necessary changes.

ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.


Related notices

  • LSN-0084-1: azure, ibm, lowlatency-5.4, gke-5.4, gke, gkeop-5.4, ibm-5.4, gkeop, aws, gcp, generic-5.4
  • USN-5362-1: linux-headers-5.13.0-1010-intel, linux-intel-5.13-tools-common, linux-modules-extra-5.13.0-1010-intel, linux-image-intel, linux-image-5.13.0-1010-intel, linux-intel-5.13-headers-5.13.0-1010, linux-cloud-tools-intel, linux-intel-5.13-tools-host, linux-modules-5.13.0-1010-intel, linux-intel-5.13-tools-5.13.0-1010, linux-intel-5.13-source-5.13.0, linux-intel, linux-cloud-tools-5.13.0-1010-intel, linux-intel-5.13-cloud-tools-common, linux-tools-intel, linux-intel-5.13, linux-intel-5.13-cloud-tools-5.13.0-1010, linux-image-unsigned-5.13.0-1010-intel, linux-headers-intel, linux-buildinfo-5.13.0-1010-intel, linux-tools-5.13.0-1010-intel