A Linux security update has been released for Ubuntu Linux 18.04 LTS.

USN-4462-1: Linux kernel vulnerability

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Ubuntu Security Notice USN-4462-1
August 18, 2020

linux-gke-5.0, linux-oem-osp1 vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS

Summary:

The system could be made to crash under certain conditions.

Software Description:
- linux-gke-5.0: Linux kernel for Google Container Engine (GKE) systems
- linux-oem-osp1: Linux kernel for OEM systems

Details:

It was discovered that the bcache subsystem in the Linux kernel did not
properly release a lock in some error conditions. A local attacker could
possibly use this to cause a denial of service.

Update instructions:

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

Ubuntu 18.04 LTS:
linux-image-5.0.0-1046-gke 5.0.0-1046.47
linux-image-5.0.0-1067-oem-osp1 5.0.0-1067.72
linux-image-gke-5.0 5.0.0.1046.31
linux-image-oem-osp1 5.0.0.1067.65

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.

References:
  https://usn.ubuntu.com/4462-1
CVE-2020-12771

Package Information:
  https://launchpad.net/ubuntu/+source/linux-gke-5.0/5.0.0-1046.47
  https://launchpad.net/ubuntu/+source/linux-oem-osp1/5.0.0-1067.72