Ubuntu 20.04 LTS USN-4751-1 Critical: Kernel Denial Of Service Threat

ubuntu

February 25, 2021

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-azure: Linux kernel for Microsoft Azure Cloud systems

- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems

- linux-kvm: Linux kernel for cloud environments

- linux-oracle: Linux kernel for Oracle Cloud systems

- linux-raspi: Linux kernel for Raspberry Pi (V8) systems

- linux-hwe-5.8: Linux hardware enablement (HWE) kernel

Details:

It was discovered that the console keyboard driver in the Linux kernel

contained a race condition. A local attacker could use this to expose

sensitive information (kernel memory). (CVE-2020-25656)

Minh Yuan discovered that the tty driver in the Linux kernel contained race

conditions when handling fonts. A local attacker could possibly use this to

expose sensitive information (kernel memory). (CVE-2020-25668)

Bodong Zhao discovered a use-after-fre...

Read the Full Advisory

Topics Covered

security advisory denial of service information leak kernel patch Ubuntu kernel system stability local attack ubuntu linux kernel

Update Instructions

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

Ubuntu 20.10:
  linux-image-5.8.0-1016-raspi    5.8.0-1016.19
  linux-image-5.8.0-1016-raspi-nolpae  5.8.0-1016.19
  linux-image-5.8.0-1019-kvm      5.8.0-1019.21
  linux-image-5.8.0-1021-oracle   5.8.0-1021.22
  linux-image-5.8.0-1023-azure    5.8.0-1023.25
  linux-image-5.8.0-1023-gcp      5.8.0-1023.24
  linux-image-5.8.0-1024-aws      5.8.0-1024.26
  linux-image-5.8.0-44-generic    5.8.0-44.50
  linux-image-5.8.0-44-generic-64k  5.8.0-44.50
  linux-image-5.8.0-44-generic-lpae  5.8.0-44.50
  linux-image-5.8.0-44-lowlatency  5.8.0-44.50
  linux-image-aws                 5.8.0.1024.26
  linux-image-azure               5.8.0.1023.23
  linux-image-gcp                 5.8.0.1023.23
  linux-image-generic             5.8.0.44.49
  linux-image-generic-64k         5.8.0.44.49
  linux-image-generic-lpae        5.8.0.44.49
  linux-image-gke                 5.8.0.1023.23
  linux-image-kvm                 5.8.0.1019.21
  linux-image-lowlatency          5.8.0.44.49
  linux-image-oem-20.04           5.8.0.44.49
  linux-image-oracle              5.8.0.1021.20
  linux-image-raspi               5.8.0.1016.19
  linux-image-raspi-nolpae        5.8.0.1016.19
  linux-image-virtual             5.8.0.44.49

Ubuntu 20.04 LTS:
  linux-image-5.8.0-44-generic    5.8.0-44.50~20.04.1
  linux-image-5.8.0-44-generic-lpae  5.8.0-44.50~20.04.1
  linux-image-5.8.0-44-lowlatency  5.8.0-44.50~20.04.1
  linux-image-generic-64k-hwe-20.04  5.8.0.44.50~20.04.30
  linux-image-generic-hwe-20.04   5.8.0.44.50~20.04.30
  linux-image-generic-lpae-hwe-20.04  5.8.0.44.50~20.04.30
  linux-image-lowlatency-hwe-20.04  5.8.0.44.50~20.04.30
  linux-image-virtual-hwe-20.04   5.8.0.44.50~20.04.30

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.