A Linux kernel security update has been released for Ubuntu Linux 20.04 LTS.

USN-4343-1: Linux kernel vulnerability

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Ubuntu Security Notice USN-4343-1
April 28, 2020

linux vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS

Summary:

Systems running on s390x architecture could be made to crash or run
programs as an administrator under certain conditions.

Software Description:
- linux: Linux kernel

Details:

Al Viro discovered that the Linux kernel for s390x systems did not properly
perform page table upgrades for kernel sections that use secondary address
mode. A local attacker could use this to cause a denial of service (system
crash) or execute arbitrary code.

Update instructions:

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

Ubuntu 20.04 LTS:
linux-image-5.4.0-28-generic 5.4.0-28.32
linux-image-5.4.0-28-generic-lpae 5.4.0-28.32
linux-image-5.4.0-28-lowlatency 5.4.0-28.32
linux-image-generic 5.4.0.28.33
linux-image-generic-lpae 5.4.0.28.33
linux-image-lowlatency 5.4.0.28.33
linux-image-oem 5.4.0.28.33
linux-image-oem-osp1 5.4.0.28.33
linux-image-virtual 5.4.0.28.33

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/4343-1
CVE-2020-11884

Package Information:
  https://launchpad.net/ubuntu/+source/linux/5.4.0-28.32