USN-4006-1: Linux kernel vulnerability

4 June 2019

linux, linux-aws, linux-gcp, linux-kvm, linux-raspi2 vulnerability

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

  • Ubuntu 18.10

Summary

A system hardening measure could be bypassed.

Software Description

  • linux - Linux kernel
  • linux-aws - Linux kernel for Amazon Web Services (AWS) systems
  • linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
  • linux-kvm - Linux kernel for cloud environments
  • linux-raspi2 - Linux kernel for Raspberry Pi 2

Details

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 18.10
linux-image-4.18.0-1012-gcp - 4.18.0-1012.13
linux-image-4.18.0-1013-kvm - 4.18.0-1013.13
linux-image-4.18.0-1015-raspi2 - 4.18.0-1015.17
linux-image-4.18.0-1017-aws - 4.18.0-1017.19
linux-image-4.18.0-21-generic - 4.18.0-21.22
linux-image-4.18.0-21-generic-lpae - 4.18.0-21.22
linux-image-4.18.0-21-lowlatency - 4.18.0-21.22
linux-image-4.18.0-21-snapdragon - 4.18.0-21.22
linux-image-aws - 4.18.0.1017.17
linux-image-gcp - 4.18.0.1012.12
linux-image-generic - 4.18.0.21.22
linux-image-generic-lpae - 4.18.0.21.22
linux-image-gke - 4.18.0.1012.12
linux-image-kvm - 4.18.0.1013.13
linux-image-lowlatency - 4.18.0.21.22
linux-image-raspi2 - 4.18.0.1015.12
linux-image-snapdragon - 4.18.0.21.22

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