USN-4320-1: Linux kernel vulnerability

6 April 2020

linux, linux-aws, linux-kvm, linux-raspi2, linux-snapdragon vulnerability

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

  • Ubuntu 16.04 LTS
  • Ubuntu 14.04 ESM

Summary

The system could be made to crash or expose sensitive information.

Software Description

  • linux - Linux kernel
  • linux-aws - Linux kernel for Amazon Web Services (AWS) systems
  • linux-kvm - Linux kernel for cloud environments
  • linux-raspi2 - Linux kernel for Raspberry Pi 2
  • linux-snapdragon - Linux kernel for Snapdragon processors
  • linux-lts-xenial - Linux hardware enablement kernel from Xenial for Trusty

Details

Al Viro discovered that the vfs layer in the Linux kernel contained a use- after-free vulnerability. A local attacker could use this to cause a denial of service (system crash) or possibly expose sensitive information (kernel memory).

Update instructions

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

Ubuntu 16.04 LTS
linux-image-4.4.0-1069-kvm - 4.4.0-1069.76
linux-image-4.4.0-1105-aws - 4.4.0-1105.116
linux-image-4.4.0-1131-raspi2 - 4.4.0-1131.140
linux-image-4.4.0-1135-snapdragon - 4.4.0-1135.143
linux-image-4.4.0-177-generic - 4.4.0-177.207
linux-image-4.4.0-177-generic-lpae - 4.4.0-177.207
linux-image-4.4.0-177-lowlatency - 4.4.0-177.207
linux-image-4.4.0-177-powerpc-e500mc - 4.4.0-177.207
linux-image-4.4.0-177-powerpc-smp - 4.4.0-177.207
linux-image-4.4.0-177-powerpc64-emb - 4.4.0-177.207
linux-image-4.4.0-177-powerpc64-smp - 4.4.0-177.207
linux-image-aws - 4.4.0.1105.109
linux-image-generic - 4.4.0.177.185
linux-image-generic-lpae - 4.4.0.177.185
linux-image-kvm - 4.4.0.1069.69
linux-image-lowlatency - 4.4.0.177.185
linux-image-powerpc-e500mc - 4.4.0.177.185
linux-image-powerpc-smp - 4.4.0.177.185
linux-image-powerpc64-emb - 4.4.0.177.185
linux-image-powerpc64-smp - 4.4.0.177.185
linux-image-raspi2 - 4.4.0.1131.131
linux-image-snapdragon - 4.4.0.1135.127
linux-image-virtual - 4.4.0.177.185
Ubuntu 14.04 ESM
linux-image-4.4.0-1065-aws - 4.4.0-1065.69
linux-image-4.4.0-177-generic - 4.4.0-177.207~14.04.1
linux-image-4.4.0-177-generic-lpae - 4.4.0-177.207~14.04.1
linux-image-4.4.0-177-lowlatency - 4.4.0-177.207~14.04.1
linux-image-4.4.0-177-powerpc-e500mc - 4.4.0-177.207~14.04.1
linux-image-4.4.0-177-powerpc-smp - 4.4.0-177.207~14.04.1
linux-image-4.4.0-177-powerpc64-emb - 4.4.0-177.207~14.04.1
linux-image-4.4.0-177-powerpc64-smp - 4.4.0-177.207~14.04.1
linux-image-aws - 4.4.0.1065.66
linux-image-generic-lpae-lts-xenial - 4.4.0.177.156
linux-image-generic-lts-xenial - 4.4.0.177.156
linux-image-lowlatency-lts-xenial - 4.4.0.177.156
linux-image-powerpc-e500mc-lts-xenial - 4.4.0.177.156
linux-image-powerpc-smp-lts-xenial - 4.4.0.177.156
linux-image-powerpc64-emb-lts-xenial - 4.4.0.177.156
linux-image-powerpc64-smp-lts-xenial - 4.4.0.177.156
linux-image-virtual-lts-xenial - 4.4.0.177.156

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