Ubuntu 16.04 LTS: USN-4254-1 Critical: Kernel Context Switch Issues

ubuntu

January 27, 2020

Several security issues were fixed in the Linux kernel.

Summary

Several security issues were fixed in the Linux kernel.

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

Details:

It was discovered that the Linux kernel did not properly clear data

structures on context switches for certain Intel graphics processors. A

local attacker could use this to expose sensitive information.

(CVE-2019-14615)

It was discovered that a race condition existed in the Virtual Video Test

Driver in the Linux kernel. An attacker with write access to /dev/video0 on

a system with the vivid module loaded could possibly use this to gain

administrative privileges. (CVE-2019-18683)

It was discovered that the btrfs file system in the Linux kernel did not

properly validate metadata, leading to a NULL pointer dereference. An

attacker could use this to specially...

Read the Full Advisory

Topics Covered

security advisory DoS Ubuntu kernel memory exhaustion context switch

Update Instructions

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

Ubuntu 16.04 LTS:
  linux-image-4.4.0-1065-kvm      4.4.0-1065.72
  linux-image-4.4.0-1101-aws      4.4.0-1101.112
  linux-image-4.4.0-1128-raspi2   4.4.0-1128.137
  linux-image-4.4.0-1132-snapdragon  4.4.0-1132.140
  linux-image-4.4.0-173-generic   4.4.0-173.203
  linux-image-4.4.0-173-generic-lpae  4.4.0-173.203
  linux-image-4.4.0-173-lowlatency  4.4.0-173.203
  linux-image-4.4.0-173-powerpc-e500mc  4.4.0-173.203
  linux-image-4.4.0-173-powerpc-smp  4.4.0-173.203
  linux-image-4.4.0-173-powerpc64-emb  4.4.0-173.203
  linux-image-4.4.0-173-powerpc64-smp  4.4.0-173.203
  linux-image-aws                 4.4.0.1101.105
  linux-image-generic             4.4.0.173.181
  linux-image-generic-lpae        4.4.0.173.181
  linux-image-kvm                 4.4.0.1065.65
  linux-image-lowlatency          4.4.0.173.181
  linux-image-powerpc-e500mc      4.4.0.173.181
  linux-image-powerpc-smp         4.4.0.173.181
  linux-image-powerpc64-emb       4.4.0.173.181
  linux-image-powerpc64-smp       4.4.0.173.181
  linux-image-raspi2              4.4.0.1128.128
  linux-image-snapdragon          4.4.0.1132.124
  linux-image-virtual             4.4.0.173.181

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.