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Ubuntu 20.04: USN-5072-1 Moderate KVM Memory Access Threats

ubuntu
Calendar Grey September 8, 2021
Dist Ubuntu Esm H88
Several vulnerabilities patched in Ubuntu's Linux kernel, necessitating upgrades for cloud providers and original equipment manufacturers.
Several security issues were fixed in the Linux kernel.

Summary

Several security issues were fixed in the Linux kernel.

Software Description:

- linux-azure-5.8: Linux kernel for Microsoft Azure cloud systems

- linux-oem-5.10: Linux kernel for OEM 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's physical

memory. (CVE-2021-3656)

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. (CVE-2021-3653)

Topics%20covered

Topics Covered

security advisory memory access ubuntu linux kernel kvm oem cloud systems

Update Instructions

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

Ubuntu 20.04 LTS:
  linux-image-5.10.0-1045-oem     5.10.0-1045.47
  linux-image-5.8.0-1041-azure    5.8.0-1041.44~20.04.1
  linux-image-azure               5.8.0.1041.44~20.04.13
  linux-image-oem-20.04           5.10.0.1045.47
  linux-image-oem-20.04b          5.10.0.1045.47

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://ubuntu.com/security/notices/USN-5072-1

CVE-2021-3653, CVE-2021-3656

Severity
important
Lowest
Low
Medium
High
Critical

September 08, 2021

Topics%20covered

Topics Covered

security advisory memory access ubuntu linux kernel kvm oem cloud systems

Package Information

https://launchpad.net/ubuntu/+source/linux-azure-5.8/5.8.0-1041.44~20.04.1
https://launchpad.net/ubuntu/+source/linux-oem-5.10/5.10.0-1045.47

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