1. Ubuntu Security Notices
  2. USN-5062-1

USN-5062-1: Linux kernel vulnerability

Publication date

8 September 2021

Overview

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

Releases

Packages

  • linux - Linux kernel
  • linux-aws - Linux kernel for Amazon Web Services (AWS) systems
  • linux-kvm - Linux kernel for cloud environments
  • linux-lts-xenial - Linux hardware enablement kernel from Xenial for Trusty

Details

Maxim Levitsky discovered that the KVM hypervisor implementation for AMD
processors in the Linux kernel did not properly prevent a guest VM from
enabling AVIC in nested guest VMs. An attacker in a guest VM could use this
to write to portions of the host’s physical memory.

Maxim Levitsky discovered that the KVM hypervisor implementation for AMD
processors in the Linux kernel did not properly prevent a guest VM from
enabling AVIC in nested guest VMs. An attacker in a guest VM could use this
to write to portions of the host’s physical memory.

Update instructions

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

Learn more about how to get the fixes.

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.

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

Ubuntu Release Package Version
16.04 xenial linux-image-4.4.0-1097-kvm –  4.4.0-1097.106  
linux-image-4.4.0-1132-aws –  4.4.0-1132.146  
linux-image-4.4.0-214-generic –  4.4.0-214.246  
linux-image-4.4.0-214-lowlatency –  4.4.0-214.246  
linux-image-aws –  4.4.0.1132.137  
linux-image-generic –  4.4.0.214.221  
linux-image-kvm –  4.4.0.1097.95  
linux-image-lowlatency –  4.4.0.214.221  
linux-image-virtual –  4.4.0.214.221  
14.04 trusty linux-image-4.4.0-1096-aws –  4.4.0-1096.101  
linux-image-4.4.0-214-generic –  4.4.0-214.246~14.04.1  
linux-image-4.4.0-214-lowlatency –  4.4.0-214.246~14.04.1  
linux-image-aws –  4.4.0.1096.94  
linux-image-generic-lts-xenial –  4.4.0.214.187  
linux-image-lowlatency-lts-xenial –  4.4.0.214.187  
linux-image-virtual-lts-xenial –  4.4.0.214.187  

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References

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