USN-4303-1: Linux kernel vulnerability

17 March 2020

linux, linux-aws, linux-kvm vulnerability

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

  • Ubuntu 16.04 LTS

Summary

The system could be made to expose sensitive information.

Software Description

  • linux - Linux kernel
  • linux-aws - Linux kernel for Amazon Web Services (AWS) systems
  • linux-kvm - Linux kernel for cloud environments

Details

Paulo Bonzini discovered that the KVM hypervisor implementation in the Linux kernel could improperly let a nested (level 2) guest access the resources of a parent (level 1) guest in certain situations. An attacker could use this to expose sensitive information.

Update instructions

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

Ubuntu 16.04 LTS
linux-image-4.4.0-1068-kvm - 4.4.0-1068.75
linux-image-4.4.0-1104-aws - 4.4.0-1104.115
linux-image-4.4.0-176-generic - 4.4.0-176.206
linux-image-4.4.0-176-generic-lpae - 4.4.0-176.206
linux-image-4.4.0-176-lowlatency - 4.4.0-176.206
linux-image-4.4.0-176-powerpc-e500mc - 4.4.0-176.206
linux-image-4.4.0-176-powerpc-smp - 4.4.0-176.206
linux-image-4.4.0-176-powerpc64-emb - 4.4.0-176.206
linux-image-4.4.0-176-powerpc64-smp - 4.4.0-176.206
linux-image-aws - 4.4.0.1104.108
linux-image-generic - 4.4.0.176.184
linux-image-generic-lpae - 4.4.0.176.184
linux-image-kvm - 4.4.0.1068.68
linux-image-lowlatency - 4.4.0.176.184
linux-image-powerpc-e500mc - 4.4.0.176.184
linux-image-powerpc-smp - 4.4.0.176.184
linux-image-powerpc64-emb - 4.4.0.176.184
linux-image-powerpc64-smp - 4.4.0.176.184
linux-image-virtual - 4.4.0.176.184

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

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