1. Ubuntu Security Notices
  2. USN-4708-1

USN-4708-1: Linux kernel vulnerabilities

Publication date

28 January 2021

Overview

Several security issues were fixed in the Linux kernel.

Releases

Packages

Details

Wen Xu discovered that the XFS filesystem implementation in the Linux
kernel did not properly track inode validations. An attacker could use this
to construct a malicious XFS image that, when mounted, could cause a denial
of service (system crash). (CVE-2018-13093)

It was discovered that the btrfs file system implementation in the Linux
kernel did not properly validate file system metadata in some situations.
An attacker could use this to construct a malicious btrfs image that, when
mounted, could cause a denial of service (system crash). (CVE-2019-19813,
CVE-2019-19816)

Bodong Zhao discovered a use-after-free in the Sun keyboard driver
implementation in the Linux kernel. A local attacker could use this to
cause a denial of service or possibly execute arbitrary code.
(

Wen Xu discovered that the XFS filesystem implementation in the Linux
kernel did not properly track inode validations. An attacker could use this
to construct a malicious XFS image that, when mounted, could cause a denial
of service (system crash). (CVE-2018-13093)

It was discovered that the btrfs file system implementation in the Linux
kernel did not properly validate file system metadata in some situations.
An attacker could use this to construct a malicious btrfs image that, when
mounted, could cause a denial of service (system crash). (CVE-2019-19813,
CVE-2019-19816)

Bodong Zhao discovered a use-after-free in the Sun keyboard driver
implementation in the Linux kernel. A local attacker could use this to
cause a denial of service or possibly execute arbitrary code.
(CVE-2020-25669)

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)

Update instructions

After a standard system update you need to reboot your computer to make all the necessary changes.

Learn more about how to get the fixes.

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.

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

Ubuntu Release Package Version
16.04 xenial linux-image-4.4.0-201-generic –  4.4.0-201.233
linux-image-4.4.0-201-generic-lpae –  4.4.0-201.233
linux-image-4.4.0-201-lowlatency –  4.4.0-201.233
linux-image-4.4.0-201-powerpc-e500mc –  4.4.0-201.233
linux-image-4.4.0-201-powerpc-smp –  4.4.0-201.233
linux-image-4.4.0-201-powerpc64-emb –  4.4.0-201.233
linux-image-4.4.0-201-powerpc64-smp –  4.4.0-201.233
linux-image-generic –  4.4.0.201.207
linux-image-generic-lpae –  4.4.0.201.207
linux-image-lowlatency –  4.4.0.201.207
linux-image-powerpc-e500mc –  4.4.0.201.207
linux-image-powerpc-smp –  4.4.0.201.207
linux-image-powerpc64-emb –  4.4.0.201.207
linux-image-powerpc64-smp –  4.4.0.201.207
linux-image-virtual –  4.4.0.201.207
14.04 trusty linux-image-4.4.0-201-generic –  4.4.0-201.233~14.04.1
linux-image-4.4.0-201-generic-lpae –  4.4.0-201.233~14.04.1
linux-image-4.4.0-201-lowlatency –  4.4.0-201.233~14.04.1
linux-image-4.4.0-201-powerpc-e500mc –  4.4.0-201.233~14.04.1
linux-image-4.4.0-201-powerpc-smp –  4.4.0-201.233~14.04.1
linux-image-4.4.0-201-powerpc64-emb –  4.4.0-201.233~14.04.1
linux-image-4.4.0-201-powerpc64-smp –  4.4.0-201.233~14.04.1
linux-image-generic-lpae-lts-xenial –  4.4.0.201.176
linux-image-generic-lts-xenial –  4.4.0.201.176
linux-image-lowlatency-lts-xenial –  4.4.0.201.176
linux-image-powerpc-e500mc-lts-xenial –  4.4.0.201.176
linux-image-powerpc-smp-lts-xenial –  4.4.0.201.176
linux-image-powerpc64-emb-lts-xenial –  4.4.0.201.176
linux-image-powerpc64-smp-lts-xenial –  4.4.0.201.176
linux-image-virtual-lts-xenial –  4.4.0.201.176

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References

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