Ubuntu 21.04 Critical: Linux Kernel Denial of Service Issues

ubuntu

September 8, 2021

Several security issues were fixed in the Linux kernel.

Summary

Several security issues were fixed in the Linux kernel.

Software Description:

- linux: Linux kernel

- linux-aws: Linux kernel for Amazon Web Services (AWS) systems

- linux-azure: Linux kernel for Microsoft Azure Cloud systems

- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems

- linux-kvm: Linux kernel for cloud environments

- linux-oracle: Linux kernel for Oracle Cloud systems

- linux-raspi: Linux kernel for Raspberry Pi (V8) systems

- linux-aws-5.11: Linux kernel for Amazon Web Services (AWS) systems

- linux-azure-5.11: Linux kernel for Microsoft Azure cloud systems

- linux-hwe-5.11: Linux hardware enablement (HWE) kernel

- linux-oracle-5.11: Linux kernel for Oracle Cloud systems

Details:

Maxim Levitsky and Paolo Bonzini discovered that the KVM hypervisor

implementation for AMD processors in the Linux kernel allowed a guest VM to

disable restrictions on VMLOAD/VMSAVE in a nested guest. An attacker in a

guest VM could use this to read or write portions of the host...

Read the Full Advisory

Topics Covered

security advisory denial of service kernel update instructions memory access ubuntu security issues

Update Instructions

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

Ubuntu 21.04:
  linux-image-5.11.0-1015-azure   5.11.0-1015.16
  linux-image-5.11.0-1015-kvm     5.11.0-1015.16
  linux-image-5.11.0-1017-aws     5.11.0-1017.18
  linux-image-5.11.0-1017-oracle  5.11.0-1017.18
  linux-image-5.11.0-1017-raspi   5.11.0-1017.18
  linux-image-5.11.0-1017-raspi-nolpae  5.11.0-1017.18
  linux-image-5.11.0-1018-gcp     5.11.0-1018.20
  linux-image-5.11.0-34-generic   5.11.0-34.36
  linux-image-5.11.0-34-generic-64k  5.11.0-34.36
  linux-image-5.11.0-34-generic-lpae  5.11.0-34.36
  linux-image-5.11.0-34-lowlatency  5.11.0-34.36
  linux-image-aws                 5.11.0.1017.18
  linux-image-azure               5.11.0.1015.16
  linux-image-gcp                 5.11.0.1018.18
  linux-image-generic             5.11.0.34.36
  linux-image-generic-64k         5.11.0.34.36
  linux-image-generic-lpae        5.11.0.34.36
  linux-image-gke                 5.11.0.1018.18
  linux-image-kvm                 5.11.0.1015.16
  linux-image-lowlatency          5.11.0.34.36
  linux-image-oem-20.04           5.11.0.34.36
  linux-image-oracle              5.11.0.1017.18
  linux-image-raspi               5.11.0.1017.15
  linux-image-raspi-nolpae        5.11.0.1017.15
  linux-image-virtual             5.11.0.34.36

Ubuntu 20.04 LTS:
  linux-image-5.11.0-1015-azure   5.11.0-1015.16~20.04.1
  linux-image-5.11.0-1017-aws     5.11.0-1017.18~20.04.1
  linux-image-5.11.0-1017-oracle  5.11.0-1017.18~20.04.1
  linux-image-5.11.0-34-generic   5.11.0-34.36~20.04.1
  linux-image-5.11.0-34-generic-64k  5.11.0-34.36~20.04.1
  linux-image-5.11.0-34-generic-lpae  5.11.0-34.36~20.04.1
  linux-image-5.11.0-34-lowlatency  5.11.0-34.36~20.04.1
  linux-image-aws                 5.11.0.1017.18~20.04.16
  linux-image-generic-64k-hwe-20.04  5.11.0.34.36~20.04.13
  linux-image-generic-hwe-20.04   5.11.0.34.36~20.04.13
  linux-image-generic-lpae-hwe-20.04  5.11.0.34.36~20.04.13
  linux-image-lowlatency-hwe-20.04  5.11.0.34.36~20.04.13
  linux-image-oracle              5.11.0.1017.18~20.04.10
  linux-image-virtual-hwe-20.04   5.11.0.34.36~20.04.13

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.