1. Ubuntu Security Notices
  2. USN-4006-2

USN-4006-2: Linux kernel (HWE) vulnerability

Publication date

4 June 2019

Overview

A system hardening measure could be bypassed.

Releases

Packages

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

Details

USN-4006-1 fixed a vulnerability in the Linux kernel for Ubuntu 18.10.
This update provides the corresponding updates for the Linux Hardware
Enablement (HWE) kernel from Ubuntu 18.10 for Ubuntu 18.04 LTS.

Federico Manuel Bento discovered that the Linux kernel did not properly
apply Address Space Layout Randomization (ASLR) in some situations for
setuid a.out binaries. A local attacker could use this to improve the
chances of exploiting an existing vulnerability in a setuid a.out binary.

As a hardening measure, this update disables a.out support.

USN-4006-1 fixed a vulnerability in the Linux kernel for Ubuntu 18.10.
This update provides the corresponding updates for the Linux Hardware
Enablement (HWE) kernel from Ubuntu 18.10 for Ubuntu 18.04 LTS.

Federico Manuel Bento discovered that the Linux kernel did not properly
apply Address Space Layout Randomization (ASLR) in some situations for
setuid a.out binaries. A local attacker could use this to improve the
chances of exploiting an existing vulnerability in a setuid a.out binary.

As a hardening measure, this update disables a.out support.

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
18.04 bionic linux-image-4.18.0-21-generic –  4.18.0-21.22~18.04.1
linux-image-4.18.0-21-generic-lpae –  4.18.0-21.22~18.04.1
linux-image-4.18.0-21-lowlatency –  4.18.0-21.22~18.04.1
linux-image-4.18.0-21-snapdragon –  4.18.0-21.22~18.04.1
linux-image-generic-hwe-18.04 –  4.18.0.21.71
linux-image-generic-lpae-hwe-18.04 –  4.18.0.21.71
linux-image-lowlatency-hwe-18.04 –  4.18.0.21.71
linux-image-snapdragon-hwe-18.04 –  4.18.0.21.71

Reduce your security exposure

Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines.

Get Ubuntu Pro

References

Have additional questions?

Talk to a member of the team ›