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             AUSCERT External Security Bulletin Redistribution

                  USN-4484-1: Linux kernel vulnerability
                             3 September 2020


        AusCERT Security Bulletin Summary

Product:           kernel
Publisher:         Ubuntu
Operating System:  Ubuntu
Impact/Access:     Root Compromise   -- Existing Account
                   Denial of Service -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-14356  

Reference:         ESB-2020.3010

Original Bulletin: 

- --------------------------BEGIN INCLUDED TEXT--------------------

USN-4484-1: Linux kernel vulnerability
02 September 2020

The system could be made to crash or run programs as an administrator.

  o Ubuntu 18.04 LTS


  o linux-aws-5.3 - Linux kernel for Amazon Web Services (AWS) systems
  o linux-gke-5.3 - Linux kernel for Google Container Engine (GKE) systems
  o linux-hwe - Linux hardware enablement (HWE) kernel
  o linux-raspi2-5.3 - Linux kernel for Raspberry Pi (V8) systems


It was discovered that the cgroup v2 subsystem in the Linux kernel did not
properly perform reference counting in some situations, leading to a NULL
pointer dereference. A local attacker could use this to cause a denial of
service or possibly gain administrative privileges.

Update instructions

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

Ubuntu 18.04

  o linux-image-5.3.0-1032-raspi2 - 5.3.0-1032.34
  o linux-image-5.3.0-1034-aws - 5.3.0-1034.36
  o linux-image-5.3.0-1034-gke - 5.3.0-1034.36
  o linux-image-5.3.0-66-generic - 5.3.0-66.60
  o linux-image-5.3.0-66-lowlatency - 5.3.0-66.60
  o linux-image-aws -
  o linux-image-gke-5.3 -
  o linux-image-gkeop-5.3 -
  o linux-image-raspi2-hwe-18.04 -

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.


  o CVE-2020-14356

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