Operating System:

[Ubuntu]

Published:

07 January 2021

Protect yourself against future threats.

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===========================================================================
             AUSCERT External Security Bulletin Redistribution

                               ESB-2021.0069
                 USN-4679-1: Linux kernel vulnerabilities
                              7 January 2021

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           kernel
Publisher:         Ubuntu
Operating System:  Ubuntu
Impact/Access:     Access Privileged Data -- Existing Account
                   Denial of Service      -- Existing Account
                   Unauthorised Access    -- Existing Account
                   Reduced Security       -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-28974 CVE-2020-27777 CVE-2020-27675
                   CVE-2020-25704 CVE-2020-25668 CVE-2020-25656

Reference:         ESB-2020.4505
                   ESB-2020.4341
                   ESB-2020.4168

Original Bulletin: 
   https://ubuntu.com/security/notices/USN-4679-1

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USN-4679-1: Linux kernel vulnerabilities
06 January 2021

Several security issues were fixed in the Linux kernel.
Releases

  o Ubuntu 20.04 LTS
  o Ubuntu 18.04 LTS

Packages

  o linux - Linux kernel
  o linux-aws - Linux kernel for Amazon Web Services (AWS) systems
  o linux-aws-5.4 - Linux kernel for Amazon Web Services (AWS) systems
  o linux-azure - Linux kernel for Microsoft Azure Cloud systems
  o linux-azure-5.4 - Linux kernel for Microsoft Azure cloud systems
  o linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
  o linux-gcp-5.4 - Linux kernel for Google Cloud Platform (GCP) systems
  o linux-gke-5.4 - Linux kernel for Google Container Engine (GKE) systems
  o linux-hwe-5.4 - Linux hardware enablement (HWE) kernel
  o linux-kvm - Linux kernel for cloud environments
  o linux-oracle - Linux kernel for Oracle Cloud systems
  o linux-oracle-5.4 - Linux kernel for Oracle Cloud systems
  o linux-raspi - Linux kernel for Raspberry Pi (V8) systems
  o linux-raspi-5.4 - Linux kernel for Raspberry Pi (V8) systems

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)

Kiyin () discovered that the perf subsystem in the Linux kernel did
not properly deallocate memory in some situations. A privileged attacker
could use this to cause a denial of service (kernel memory exhaustion).
(CVE-2020-25704)

Jinoh Kang discovered that the Xen event channel infrastructure in the
Linux kernel contained a race condition. An attacker in guest could
possibly use this to cause a denial of service (dom0 crash).
(CVE-2020-27675)

Daniel Axtens discovered that PowerPC RTAS implementation in the Linux
kernel did not properly restrict memory accesses in some situations. A
privileged local attacker could use this to arbitrarily modify kernel
memory, potentially bypassing kernel lockdown restrictions.
(CVE-2020-27777)

Minh Yuan discovered that the framebuffer console driver in the Linux
kernel did not properly handle fonts in some conditions. A local attacker
could use this to cause a denial of service (system crash) or possibly
expose sensitive information (kernel memory). (CVE-2020-28974)

Update instructions

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

Ubuntu 20.04

  o linux-image-5.4.0-1026-raspi - 5.4.0-1026.29
  o linux-image-5.4.0-1031-kvm - 5.4.0-1031.32
  o linux-image-5.4.0-1033-gcp - 5.4.0-1033.35
  o linux-image-5.4.0-1034-aws - 5.4.0-1034.35
  o linux-image-5.4.0-1034-oracle - 5.4.0-1034.36
  o linux-image-5.4.0-1035-azure - 5.4.0-1035.36
  o linux-image-5.4.0-59-generic - 5.4.0-59.65
  o linux-image-5.4.0-59-generic-lpae - 5.4.0-59.65
  o linux-image-5.4.0-59-lowlatency - 5.4.0-59.65
  o linux-image-aws - 5.4.0.1034.35
  o linux-image-azure - 5.4.0.1035.33
  o linux-image-gcp - 5.4.0.1033.42
  o linux-image-generic - 5.4.0.59.62
  o linux-image-generic-lpae - 5.4.0.59.62
  o linux-image-kvm - 5.4.0.1031.29
  o linux-image-lowlatency - 5.4.0.59.62
  o linux-image-oem - 5.4.0.59.62
  o linux-image-oem-osp1 - 5.4.0.59.62
  o linux-image-oracle - 5.4.0.1034.31
  o linux-image-raspi - 5.4.0.1026.61
  o linux-image-raspi2 - 5.4.0.1026.61
  o linux-image-virtual - 5.4.0.59.62

Ubuntu 18.04

  o linux-image-5.4.0-1026-raspi - 5.4.0-1026.29~18.04.1
  o linux-image-5.4.0-1033-gcp - 5.4.0-1033.35~18.04.1
  o linux-image-5.4.0-1033-gke - 5.4.0-1033.35~18.04.1
  o linux-image-5.4.0-1034-aws - 5.4.0-1034.35~18.04.1
  o linux-image-5.4.0-1034-oracle - 5.4.0-1034.36~18.04.1
  o linux-image-5.4.0-1035-azure - 5.4.0-1035.36~18.04.1
  o linux-image-5.4.0-59-generic - 5.4.0-59.65~18.04.1
  o linux-image-5.4.0-59-generic-lpae - 5.4.0-59.65~18.04.1
  o linux-image-5.4.0-59-lowlatency - 5.4.0-59.65~18.04.1
  o linux-image-aws - 5.4.0.1034.19
  o linux-image-azure - 5.4.0.1035.17
  o linux-image-gcp - 5.4.0.1033.21
  o linux-image-generic-hwe-18.04 - 5.4.0.59.65~18.04.54
  o linux-image-generic-lpae-hwe-18.04 - 5.4.0.59.65~18.04.54
  o linux-image-gke-5.4 - 5.4.0.1033.35~18.04.2
  o linux-image-lowlatency-hwe-18.04 - 5.4.0.59.65~18.04.54
  o linux-image-oem - 5.4.0.59.65~18.04.54
  o linux-image-oem-osp1 - 5.4.0.59.65~18.04.54
  o linux-image-oracle - 5.4.0.1034.36~18.04.18
  o linux-image-raspi-hwe-18.04 - 5.4.0.1026.30
  o linux-image-snapdragon-hwe-18.04 - 5.4.0.59.65~18.04.54
  o linux-image-virtual-hwe-18.04 - 5.4.0.59.65~18.04.54

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.

References

  o CVE-2020-28974
  o CVE-2020-25656
  o CVE-2020-25704
  o CVE-2020-27675
  o CVE-2020-27777
  o CVE-2020-25668

Related notices

  o USN-4681-1 : linux-image-powerpc64-smp,
    linux-image-generic-lpae-lts-xenial, linux-image-4.4.0-1143-raspi2,
    linux-image-4.4.0-198-powerpc64-smp, linux-image-4.4.0-1147-snapdragon,
    linux-lts-xenial, linux-snapdragon, linux,
    linux-image-4.4.0-198-powerpc64-emb, linux-image-virtual-lts-xenial,
    linux-image-4.4.0-198-powerpc-smp, linux-image-lowlatency, linux-kvm,
    linux-image-4.4.0-1083-aws, linux-image-4.4.0-198-powerpc-e500mc,
    linux-image-snapdragon, linux-raspi2, linux-image-kvm,
    linux-image-powerpc-smp-lts-xenial, linux-image-powerpc-e500mc,
    linux-image-powerpc-smp, linux-image-virtual,
    linux-image-lowlatency-lts-xenial, linux-image-4.4.0-198-generic-lpae,
    linux-image-generic-lts-xenial, linux-image-4.4.0-1119-aws,
    linux-image-4.4.0-198-lowlatency, linux-image-raspi2,
    linux-image-generic-lpae, linux-image-powerpc-e500mc-lts-xenial,
    linux-image-powerpc64-smp-lts-xenial, linux-aws,
    linux-image-4.4.0-198-generic, linux-image-generic,
    linux-image-powerpc64-emb, linux-image-powerpc64-emb-lts-xenial,
    linux-image-aws, linux-image-4.4.0-1085-kvm
  o USN-4680-1 : linux-image-4.15.0-1091-aws, linux-image-4.15.0-1077-raspi2,
    linux-image-powerpc64-smp, linux-image-oracle-lts-18.04,
    linux-image-4.15.0-1094-snapdragon, linux-gcp-4.15, linux-snapdragon,
    linux, linux-gcp, linux-image-azure, linux-azure-4.15,
    linux-image-4.15.0-1077-gke, linux-image-generic-lpae-hwe-16.04,
    linux-image-4.15.0-1091-gcp, linux-image-4.15.0-129-generic-lpae,
    linux-gke-4.15, linux-image-4.15.0-1082-kvm, linux-kvm, linux-image-gke,
    linux-image-4.15.0-1062-oracle, linux-image-snapdragon,
    linux-image-gcp-lts-18.04, linux-raspi2, linux-image-4.15.0-129-generic,
    linux-image-aws-hwe, linux-image-oracle, linux-image-kvm,
    linux-image-4.15.0-1103-azure, linux-image-oem, linux-image-powerpc-e500mc,
    linux-image-powerpc-smp, linux-image-virtual,
    linux-image-virtual-hwe-16.04, linux-image-aws-lts-18.04,
    linux-image-raspi2, linux-image-azure-lts-18.04,
    linux-image-generic-hwe-16.04, linux-image-generic-lpae, linux-oracle,
    linux-aws, linux-azure, linux-hwe, linux-image-gcp, linux-image-generic,
    linux-image-gke-4.15, linux-image-lowlatency-hwe-16.04,
    linux-image-powerpc64-emb, linux-aws-hwe,
    linux-image-4.15.0-129-lowlatency, linux-image-lowlatency

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