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             AUSCERT External Security Bulletin Redistribution

               LSN-0079-1: Kernel Live Patch Security Notice
                               28 July 2021


        AusCERT Security Bulletin Summary

Product:           kernel
Publisher:         Ubuntu
Operating System:  Ubuntu
Impact/Access:     Root Compromise                 -- Existing Account
                   Execute Arbitrary Code/Commands -- Existing Account
                   Denial of Service               -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-33909 CVE-2021-3600 

Reference:         ESB-2021.2532

Original Bulletin: 

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

LSN-0079-1: Kernel Live Patch Security Notice
26 July 2021

Several security issues were fixed in the kernel.

  o Ubuntu 20.04 LTS
  o Ubuntu 18.04 LTS
  o Ubuntu 16.04 ESM
  o Ubuntu 14.04 ESM

Software Description

  o gcp - Linux kernel for Google Cloud Platform (GCP) systems - (>= 5.4.0-1009)
  o generic-4.15 - Linux kernel - (>= 4.15.0-69)
  o generic-4.4 - Linux kernel - (>= 4.4.0-168, >= 4.4.0-168)
  o generic-5.4 - Linux kernel - (>= 5.4.0-26, >= 5.4.0-26)
  o gke - Linux kernel for Google Container Engine (GKE) systems - (>= 5.4.0-1033)
  o gke-4.15 - Linux kernel for Google Container Engine (GKE) systems - (>= 4.15.0-1076)
  o gke-5.4 - Linux kernel for Google Container Engine (GKE) systems - (>= 5.4.0-1009)
  o gkeop - Linux kernel for Google Container Engine (GKE) systems - (>= 5.4.0-1009)
  o gkeop-5.4 - Linux kernel for Google Container Engine (GKE) systems - (>= 5.4.0-1007)
  o lowlatency-4.15 - Linux kernel - (>= 4.15.0-69)
  o lowlatency-4.4 - Linux kernel - (>= 4.4.0-168, >= 4.4.0-168)
  o lowlatency-5.4 - Linux kernel - (>= 5.4.0-26, >= 5.4.0-26)
  o oem - Linux kernel for OEM systems - (>= 4.15.0-1063)


It was discovered that the eBPF implementation in the Linux kernel did not
properly track bounds information for 32 bit registers when performing div
and mod operations. A local attacker could use this to possibly execute
arbitrary code.( CVE-2021-3600 )

It was discovered that the virtual file system implementation in the Linux
kernel contained an unsigned to signed integer conversion error. A local
attacker could use this to cause a denial of service (system crash) or
execute arbitrary code.( CVE-2021-33909 )

Checking update status

The problem can be corrected in these Livepatch versions:

  Kernel type   20.04 18.04 16.04 14.04
gcp             79.1  -     -     -
generic-4.15    -     79.1  -     -
generic-4.4     -     -     79.1  79.1
generic-5.4     79.1  79.1  -     -
gke             79.1  -     -     -
gke-4.15        -     79.1  -     -
gke-5.4         -     79.1  -     -
gkeop           79.1  -     -     -
gkeop-5.4       -     79.1  -     -
lowlatency-4.15 -     79.1  -     -
lowlatency-4.4  -     -     79.1  79.1
lowlatency-5.4  79.1  79.1  -     -
oem             -     79.1  -     -

To check your kernel type and Livepatch version, enter this command:

canonical-livepatch status


  o CVE-2021-3600
  o CVE-2021-33909

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