USN-3488-1: Linux kernel (Azure) vulnerability

Ubuntu Security Notice USN-3488-1

21st November, 2017

linux-azure vulnerability

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

  • Ubuntu 16.04 LTS

Summary

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

Software description

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

Details

It was discovered that the KVM subsystem in the Linux kernel did not
properly keep track of nested levels in guest page tables. A local attacker
in a guest VM could use this to cause a denial of service (host OS crash)
or possibly execute arbitrary code in the host OS.

Update instructions

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

Ubuntu 16.04 LTS:
linux-image-4.11.0-1015-azure 4.11.0-1015.15
linux-image-azure 4.11.0.1015.15

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

CVE-2017-12188