A Linux kernel security update has been released for Ubuntu Linux 18.04 LTS and 20.04 LTS.

USN-5116-1: Linux kernel vulnerabilities

=========================================================================
Ubuntu Security Notice USN-5116-1
October 20, 2021

linux, linux-bluefield, linux-gcp-5.4, linux-hwe-5.4, linux-kvm
vulnerabilities
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux: Linux kernel
- linux-bluefield: Linux kernel for NVIDIA BlueField platforms
- linux-kvm: Linux kernel for cloud environments
- linux-gcp-5.4: Linux kernel for Google Cloud Platform (GCP) systems
- linux-hwe-5.4: Linux hardware enablement (HWE) kernel

Details:

It was discovered that a race condition existed in the Atheros Ath9k WiFi
driver in the Linux kernel. An attacker could possibly use this to expose
sensitive information (WiFi network traffic). (CVE-2020-3702)

Alois Wohlschlager discovered that the overlay file system in the Linux
kernel did not restrict private clones in some situations. An attacker
could use this to expose sensitive information. (CVE-2021-3732)

It was discovered that the KVM hypervisor implementation in the Linux
kernel did not properly compute the access permissions for shadow pages in
some situations. A local attacker could use this to cause a denial of
service. (CVE-2021-38198)

It was discovered that the Xilinx 10/100 Ethernet Lite device driver in the
Linux kernel could report pointer addresses in some situations. An attacker
could use this information to ease the exploitation of another
vulnerability. (CVE-2021-38205)

It was discovered that the ext4 file system in the Linux kernel contained a
race condition when writing xattrs to an inode. A local attacker could use
this to cause a denial of service or possibly gain administrative
privileges. (CVE-2021-40490)

It was discovered that the 6pack network protocol driver in the Linux
kernel did not properly perform validation checks. A privileged attacker
could use this to cause a denial of service (system crash) or execute
arbitrary code. (CVE-2021-42008)

Update instructions:

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

Ubuntu 20.04 LTS:
linux-image-5.4.0-1020-bluefield 5.4.0-1020.23
linux-image-5.4.0-1048-kvm 5.4.0-1048.50
linux-image-5.4.0-89-generic 5.4.0-89.100
linux-image-5.4.0-89-generic-lpae 5.4.0-89.100
linux-image-5.4.0-89-lowlatency 5.4.0-89.100
linux-image-bluefield 5.4.0.1020.21
linux-image-generic 5.4.0.89.93
linux-image-generic-lpae 5.4.0.89.93
linux-image-kvm 5.4.0.1048.47
linux-image-lowlatency 5.4.0.89.93
linux-image-oem 5.4.0.89.93
linux-image-oem-osp1 5.4.0.89.93
linux-image-virtual 5.4.0.89.93

Ubuntu 18.04 LTS:
linux-image-5.4.0-1055-gcp 5.4.0-1055.59~18.04.1
linux-image-5.4.0-89-generic 5.4.0-89.100~18.04.1
linux-image-5.4.0-89-generic-lpae 5.4.0-89.100~18.04.1
linux-image-5.4.0-89-lowlatency 5.4.0-89.100~18.04.1
linux-image-gcp 5.4.0.1055.41
linux-image-generic-hwe-18.04 5.4.0.89.100~18.04.79
linux-image-generic-lpae-hwe-18.04 5.4.0.89.100~18.04.79
linux-image-lowlatency-hwe-18.04 5.4.0.89.100~18.04.79
linux-image-oem 5.4.0.89.100~18.04.79
linux-image-oem-osp1 5.4.0.89.100~18.04.79
linux-image-snapdragon-hwe-18.04 5.4.0.89.100~18.04.79
linux-image-virtual-hwe-18.04 5.4.0.89.100~18.04.79

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-5116-1
CVE-2020-3702, CVE-2021-3732, CVE-2021-38198, CVE-2021-38205,
CVE-2021-40490, CVE-2021-42008

Package Information:
  https://launchpad.net/ubuntu/+source/linux/5.4.0-89.100
  https://launchpad.net/ubuntu/+source/linux-bluefield/5.4.0-1020.23
  https://launchpad.net/ubuntu/+source/linux-kvm/5.4.0-1048.50
  https://launchpad.net/ubuntu/+source/linux-gcp-5.4/5.4.0-1055.59~18.04.1
  https://launchpad.net/ubuntu/+source/linux-hwe-5.4/5.4.0-89.100~18.04.1

--cC1j3YGnE6qIamoa