Ubuntu 18.04 LTS USN-5073-1 Critical: KVM Memory Disclosure Threat

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-4.15: Linux kernel for Microsoft Azure Cloud systems

- linux-dell300x: Linux kernel for Dell 300x platforms

- linux-kvm: Linux kernel for cloud environments

- linux-oracle: Linux kernel for Oracle Cloud systems

- linux-snapdragon: Linux kernel for Qualcomm Snapdragon processors- linux-aws-hwe: Linux kernel for Amazon Web Services (AWS-HWE) systems

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

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

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's physical

memory. (CVE-2021-3656)

Maxim Levitsky discovered ...

Read the Full Advisory

Topics Covered

security advisory critical DoS Ubuntu memory disclosure kernel issues KVM

Update Instructions

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

Ubuntu 18.04 LTS:
  linux-image-4.15.0-1027-dell300x  4.15.0-1027.32
  linux-image-4.15.0-1080-oracle  4.15.0-1080.88
  linux-image-4.15.0-1099-kvm     4.15.0-1099.101
  linux-image-4.15.0-1111-aws     4.15.0-1111.118
  linux-image-4.15.0-1112-snapdragon  4.15.0-1112.121
  linux-image-4.15.0-1123-azure   4.15.0-1123.136
  linux-image-4.15.0-156-generic  4.15.0-156.163
  linux-image-4.15.0-156-generic-lpae  4.15.0-156.163
  linux-image-4.15.0-156-lowlatency  4.15.0-156.163
  linux-image-aws-lts-18.04       4.15.0.1111.114
  linux-image-azure-lts-18.04     4.15.0.1123.96
  linux-image-dell300x            4.15.0.1027.29
  linux-image-generic             4.15.0.156.145
  linux-image-generic-lpae        4.15.0.156.145
  linux-image-kvm                 4.15.0.1099.95
  linux-image-lowlatency          4.15.0.156.145
  linux-image-oracle-lts-18.04    4.15.0.1080.90
  linux-image-snapdragon          4.15.0.1112.115
  linux-image-virtual             4.15.0.156.145

Ubuntu 16.04 ESM:
  linux-image-4.15.0-1080-oracle  4.15.0-1080.88~16.04.1
  linux-image-4.15.0-1111-aws     4.15.0-1111.118~16.04.1
  linux-image-4.15.0-1123-azure   4.15.0-1123.136~16.04.1
  linux-image-4.15.0-156-generic  4.15.0-156.163~16.04.1
  linux-image-4.15.0-156-lowlatency  4.15.0-156.163~16.04.1
  linux-image-aws-hwe             4.15.0.1111.102
  linux-image-azure               4.15.0.1123.114
  linux-image-generic-hwe-16.04   4.15.0.156.149
  linux-image-lowlatency-hwe-16.04  4.15.0.156.149
  linux-image-oem                 4.15.0.156.149
  linux-image-oracle              4.15.0.1080.68
  linux-image-virtual-hwe-16.04   4.15.0.156.149

Ubuntu 14.04 ESM:
  linux-image-4.15.0-1123-azure   4.15.0-1123.136~14.04.1
  linux-image-azure               4.15.0.1123.96

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.