1. Ubuntu Security Notices
  2. USN-4748-1

USN-4748-1: Linux kernel vulnerabilities

Publication date

25 February 2021

Overview

Several security issues were fixed in the Linux kernel.

Releases

Packages

Details

It was discovered that the jfs file system implementation in the Linux
kernel contained an out-of-bounds read vulnerability. A local attacker
could use this to possibly cause a denial of service (system crash).
(CVE-2020-27815)

It was discovered that the memory management subsystem in the Linux kernel
did not properly handle copy-on-write operations in some situations. A
local attacker could possibly use this to gain unintended write access to
read-only memory pages. (CVE-2020-29374)

Michael Kurth and Pawel Wieczorkiewicz discovered that the Xen event
processing backend in the Linux kernel did not properly limit the number of
events queued. An attacker in a guest VM could use this to cause a denial
of service in the host OS. (CVE-2020-29568)

Jann Horn discovered that the tty subsystem of the Linux kernel did...

It was discovered that the jfs file system implementation in the Linux
kernel contained an out-of-bounds read vulnerability. A local attacker
could use this to possibly cause a denial of service (system crash).
(CVE-2020-27815)

It was discovered that the memory management subsystem in the Linux kernel
did not properly handle copy-on-write operations in some situations. A
local attacker could possibly use this to gain unintended write access to
read-only memory pages. (CVE-2020-29374)

Michael Kurth and Pawel Wieczorkiewicz discovered that the Xen event
processing backend in the Linux kernel did not properly limit the number of
events queued. An attacker in a guest VM could use this to cause a denial
of service in the host OS. (CVE-2020-29568)

Jann Horn discovered that the tty subsystem of the Linux kernel did not use
consistent locking in some situations, leading to a read-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly expose sensitive information (kernel memory).
(CVE-2020-29660)

Jann Horn discovered a race condition in the tty subsystem of the Linux
kernel in the locking for the TIOCSPGRP ioctl(), leading to a use-after-
free vulnerability. A local attacker could use this to cause a denial of
service (system crash) or possibly execute arbitrary code. (CVE-2020-29661)

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-4.4.0-1088-kvm –  4.4.0-1088.97
linux-image-4.4.0-1122-aws –  4.4.0-1122.136
linux-image-4.4.0-1146-raspi2 –  4.4.0-1146.156
linux-image-4.4.0-1150-snapdragon –  4.4.0-1150.160
linux-image-4.4.0-203-generic –  4.4.0-203.235
linux-image-4.4.0-203-generic-lpae –  4.4.0-203.235
linux-image-4.4.0-203-lowlatency –  4.4.0-203.235
linux-image-4.4.0-203-powerpc-e500mc –  4.4.0-203.235
linux-image-4.4.0-203-powerpc-smp –  4.4.0-203.235
linux-image-4.4.0-203-powerpc64-emb –  4.4.0-203.235
linux-image-4.4.0-203-powerpc64-smp –  4.4.0-203.235
linux-image-aws –  4.4.0.1122.127
linux-image-generic –  4.4.0.203.209
linux-image-generic-lpae –  4.4.0.203.209
linux-image-kvm –  4.4.0.1088.86
linux-image-lowlatency –  4.4.0.203.209
linux-image-powerpc-e500mc –  4.4.0.203.209
linux-image-powerpc-smp –  4.4.0.203.209
linux-image-powerpc64-emb –  4.4.0.203.209
linux-image-powerpc64-smp –  4.4.0.203.209
linux-image-raspi2 –  4.4.0.1146.146
linux-image-snapdragon –  4.4.0.1150.142
linux-image-virtual –  4.4.0.203.209
14.04 trusty linux-image-4.4.0-1086-aws –  4.4.0-1086.90
linux-image-4.4.0-203-generic –  4.4.0-203.235~14.04.1
linux-image-4.4.0-203-generic-lpae –  4.4.0-203.235~14.04.1
linux-image-4.4.0-203-lowlatency –  4.4.0-203.235~14.04.1
linux-image-4.4.0-203-powerpc-e500mc –  4.4.0-203.235~14.04.1
linux-image-4.4.0-203-powerpc-smp –  4.4.0-203.235~14.04.1
linux-image-4.4.0-203-powerpc64-emb –  4.4.0-203.235~14.04.1
linux-image-4.4.0-203-powerpc64-smp –  4.4.0-203.235~14.04.1
linux-image-aws –  4.4.0.1086.83
linux-image-generic-lpae-lts-xenial –  4.4.0.203.177
linux-image-generic-lts-xenial –  4.4.0.203.177
linux-image-lowlatency-lts-xenial –  4.4.0.203.177
linux-image-powerpc-e500mc-lts-xenial –  4.4.0.203.177
linux-image-powerpc-smp-lts-xenial –  4.4.0.203.177
linux-image-powerpc64-emb-lts-xenial –  4.4.0.203.177
linux-image-powerpc64-smp-lts-xenial –  4.4.0.203.177
linux-image-virtual-lts-xenial –  4.4.0.203.177

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References

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