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             AUSCERT External Security Bulletin Redistribution

              USN-4983-1: Linux kernel (OEM) vulnerabilities
                                4 June 2021


        AusCERT Security Bulletin Summary

Product:           linux kernel (OEM)
Publisher:         Ubuntu
Operating System:  Ubuntu
Impact/Access:     Execute Arbitrary Code/Commands -- Existing Account
                   Increased Privileges            -- Existing Account
                   Denial of Service               -- Existing Account
                   Access Confidential Data        -- Existing Account
                   Reduced Security                -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-33200 CVE-2021-31829 CVE-2021-29155

Reference:         ESB-2021.1919

Original Bulletin: 

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USN-4983-1: Linux kernel (OEM) vulnerabilities
03 June 2021

Several security issues were fixed in the Linux kernel.

  o Ubuntu 20.04 LTS


  o linux-oem-5.10 - Linux kernel for OEM systems


Piotr Krysiuk discovered that the eBPF implementation in the Linux kernel
did not properly enforce limits for pointer operations. A local attacker
could use this to cause a denial of service (system crash) or possibly
execute arbitrary code. ( CVE-2021-33200 )

Piotr Krysiuk and Benedict Schlueter discovered that the eBPF
implementation in the Linux kernel performed out of bounds speculation on
pointer arithmetic. A local attacker could use this to expose sensitive
information. ( CVE-2021-29155 )

Piotr Krysiuk discovered that the eBPF implementation in the Linux kernel
did not properly prevent speculative loads in certain situations. A local
attacker could use this to expose sensitive information (kernel memory).
( CVE-2021-31829 )

Reiji Watanabe discovered that the KVM VMX implementation in the Linux
kernel did not properly prevent user space from tampering with an array
index value, leading to a potential out-of-bounds write. A local attacker
could use this to cause a denial of service (system crash) or possibly
execute arbitrary code. ( CVE-2021-3501 )

Update instructions

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

Ubuntu 20.04

  o linux-image-oem-20.04b -
  o linux-image-oem-20.04 -
  o linux-image-5.10.0-1029-oem - 5.10.0-1029.30

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.


  o CVE-2021-29155
  o CVE-2021-3501
  o CVE-2021-31829
  o CVE-2021-33200

Related notices

  o USN-4977-1 : linux-image-5.11.0-1008-kvm, linux-image-aws,
    linux-image-generic-hwe-20.04, linux-oracle, linux-image-5.11.0-1008-gcp,
    linux, linux-image-generic-64k-hwe-20.04-edge,
    linux-image-lowlatency-hwe-20.04, linux-image-5.11.0-1008-aws,
    linux-image-oracle, linux-image-5.11.0-1009-raspi, linux-kvm,
    linux-image-5.11.0-18-generic-lpae, linux-image-5.11.0-1006-azure,
    linux-image-gcp, linux-image-generic, linux-image-kvm, linux-image-gke,
    linux-image-5.11.0-1009-raspi-nolpae, linux-image-lowlatency,
    linux-image-5.11.0-18-generic, linux-image-5.11.0-18-lowlatency,
    linux-image-5.11.0-18-generic-64k, linux-image-oem-20.04,
    linux-image-raspi-nolpae, linux-gcp, linux-image-generic-lpae-hwe-20.04,
    linux-image-generic-hwe-20.04-edge, linux-raspi, linux-image-raspi,
    linux-azure, linux-image-virtual-hwe-20.04-edge,
    linux-image-generic-64k-hwe-20.04, linux-image-5.11.0-1007-oracle,
    linux-image-lowlatency-hwe-20.04-edge, linux-image-virtual-hwe-20.04,
    linux-image-azure, linux-image-generic-lpae, linux-image-virtual,
    linux-aws, linux-image-generic-lpae-hwe-20.04-edge, linux-image-generic-64k

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