USN-4007-1: Linux kernel vulnerability

4 June 2019

linux, linux-aws, linux-gcp, linux-kvm, linux-oem, linux-oracle, linux-raspi2, linux-snapdragon 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 - 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-oem - Linux kernel for OEM processors
  • linux-oracle - Linux kernel for Oracle Cloud systems
  • linux-raspi2 - Linux kernel for Raspberry Pi 2
  • linux-snapdragon - Linux kernel for Snapdragon processors

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 18.04 LTS
linux-image-4.15.0-1014-oracle - 4.15.0-1014.16
linux-image-4.15.0-1033-gcp - 4.15.0-1033.35
linux-image-4.15.0-1035-kvm - 4.15.0-1035.35
linux-image-4.15.0-1037-raspi2 - 4.15.0-1037.39
linux-image-4.15.0-1039-oem - 4.15.0-1039.44
linux-image-4.15.0-1040-aws - 4.15.0-1040.42
linux-image-4.15.0-1054-snapdragon - 4.15.0-1054.58
linux-image-4.15.0-51-generic - 4.15.0-51.55
linux-image-4.15.0-51-generic-lpae - 4.15.0-51.55
linux-image-4.15.0-51-lowlatency - 4.15.0-51.55
linux-image-aws - 4.15.0.1040.39
linux-image-gcp - 4.15.0.1033.35
linux-image-generic - 4.15.0.51.53
linux-image-generic-lpae - 4.15.0.51.53
linux-image-kvm - 4.15.0.1035.35
linux-image-lowlatency - 4.15.0.51.53
linux-image-oem - 4.15.0.1039.43
linux-image-oracle - 4.15.0.1014.17
linux-image-raspi2 - 4.15.0.1037.35
linux-image-snapdragon - 4.15.0.1054.57

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