USN-4324-1: Linux kernel vulnerabilities

07 April 2020

Several security issues were fixed in the Linux kernel.

Releases

Packages

  • linux-aws - Linux kernel for Amazon Web Services (AWS) systems
  • linux-aws-hwe - Linux kernel for Amazon Web Services (AWS-HWE) systems
  • linux-azure - Linux kernel for Microsoft Azure Cloud systems
  • linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
  • linux-gke-4.15 - Linux kernel for Google Container Engine (GKE) 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

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). (CVE-2020-8428)

Shijie Luo discovered that the ext4 file system implementation in the Linux
kernel did not properly check for a too-large journal size. An attacker
could use this to construct a malicious ext4 image that, when mounted,
could cause a denial of service (soft lockup). (CVE-2020-8992)

Update instructions

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

Ubuntu 18.04
Ubuntu 16.04
Ubuntu 14.04

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.