A Linux kernel security update has been released for Ubuntu Linux 16.04 ESM and 18.04 LTS.

USN-6081-1: Linux kernel vulnerabilities

==========================================================================
Ubuntu Security Notice USN-6081-1
May 16, 2023

linux, linux-aws, linux-aws-hwe, linux-kvm vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS
- Ubuntu 16.04 ESM

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux: Linux kernel
- linux-aws: Linux kernel for Amazon Web Services (AWS) systems
- linux-kvm: Linux kernel for cloud environments
- linux-aws-hwe: Linux kernel for Amazon Web Services (AWS-HWE) systems

Details:

Jordy Zomer and Alexandra Sandulescu discovered that the Linux kernel did
not properly implement speculative execution barriers in usercopy functions
in certain situations. A local attacker could use this to expose sensitive
information (kernel memory). (CVE-2023-0459)

Xingyuan Mo discovered that the x86 KVM implementation in the Linux kernel
did not properly initialize some data structures. A local attacker could
use this to expose sensitive information (kernel memory). (CVE-2023-1513)

It was discovered that a use-after-free vulnerability existed in the iSCSI
TCP implementation in the Linux kernel. A local attacker could possibly use
this to cause a denial of service (system crash). (CVE-2023-2162)

It was discovered that the NET/ROM protocol implementation in the Linux
kernel contained a race condition in some situations, 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-2023-32269)

Duoming Zhou discovered that a race condition existed in the infrared
receiver/transceiver driver in the Linux kernel, leading to a use-after-
free vulnerability. A privileged attacker could use this to cause a denial
of service (system crash) or possibly execute arbitrary code.
(CVE-2023-1118)

Update instructions:

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

Ubuntu 18.04 LTS:
linux-image-4.15.0-1140-kvm 4.15.0-1140.145
linux-image-4.15.0-1156-aws 4.15.0-1156.169
linux-image-4.15.0-211-generic 4.15.0-211.222
linux-image-4.15.0-211-generic-lpae 4.15.0-211.222
linux-image-4.15.0-211-lowlatency 4.15.0-211.222
linux-image-aws-lts-18.04 4.15.0.1156.154
linux-image-generic 4.15.0.211.194
linux-image-generic-lpae 4.15.0.211.194
linux-image-kvm 4.15.0.1140.131
linux-image-lowlatency 4.15.0.211.194
linux-image-virtual 4.15.0.211.194

Ubuntu 16.04 ESM:
linux-image-4.15.0-1156-aws 4.15.0-1156.169~16.04.1
linux-image-aws-hwe 4.15.0.1156.139

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:
https://ubuntu.com/security/notices/USN-6081-1
CVE-2023-0459, CVE-2023-1118, CVE-2023-1513, CVE-2023-2162,
CVE-2023-32269

Package Information:
https://launchpad.net/ubuntu/+source/linux/4.15.0-211.222
https://launchpad.net/ubuntu/+source/linux-aws/4.15.0-1156.169
https://launchpad.net/ubuntu/+source/linux-kvm/4.15.0-1140.145