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

4 June 2019

linux-hwe vulnerability

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

  • Ubuntu 18.04 LTS

Summary

A system hardening measure could be bypassed.

Software Description

  • 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.

Update instructions

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

Ubuntu 18.04 LTS
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

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