A Linux kernel security update has been released for Ubuntu Linux 21.04.

USN-4977-1: Linux kernel vulnerabilities

==========================================================================
Ubuntu Security Notice USN-4977-1
June 02, 2021

linux, linux-aws, linux-azure, linux-gcp, linux-kvm, linux-oracle
vulnerabilities
==========================================================================

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

- Ubuntu 21.04

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-azure: Linux kernel for Microsoft Azure Cloud systems
- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems
- linux-kvm: Linux kernel for cloud environments
- linux-oracle: Linux kernel for Oracle Cloud systems

Details:

Kiyin (尹亮) discovered that the NFC LLCP protocol implementation in the
Linux kernel contained a reference counting error. A local attacker could
use this to cause a denial of service (system crash). (CVE-2020-25670)

Kiyin (尹亮) discovered that the NFC LLCP protocol implementation in the
Linux kernel did not properly deallocate memory in certain error
situations. A local attacker could use this to cause a denial of service
(memory exhaustion). (CVE-2020-25671, CVE-2020-25672)

Kiyin (尹亮) discovered that the NFC LLCP protocol implementation in the
Linux kernel did not properly handle error conditions in some situations,
leading to an infinite loop. A local attacker could use this to cause a
denial of service. (CVE-2020-25673)

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)

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 versions:

Ubuntu 21.04:
linux-image-5.11.0-1006-azure 5.11.0-1006.6
linux-image-5.11.0-1007-oracle 5.11.0-1007.7
linux-image-5.11.0-1008-aws 5.11.0-1008.8
linux-image-5.11.0-1008-gcp 5.11.0-1008.9
linux-image-5.11.0-1008-kvm 5.11.0-1008.8
linux-image-5.11.0-18-generic 5.11.0-18.19
linux-image-5.11.0-18-generic-64k 5.11.0-18.19
linux-image-5.11.0-18-generic-lpae 5.11.0-18.19
linux-image-5.11.0-18-lowlatency 5.11.0-18.19
linux-image-aws 5.11.0.1008.8
linux-image-azure 5.11.0.1006.6
linux-image-gcp 5.11.0.1008.8
linux-image-generic 5.11.0.18.19
linux-image-generic-64k 5.11.0.18.19
linux-image-generic-lpae 5.11.0.18.19
linux-image-gke 5.11.0.1008.8
linux-image-kvm 5.11.0.1008.8
linux-image-lowlatency 5.11.0.18.19
linux-image-oracle 5.11.0.1007.7
linux-image-virtual 5.11.0.18.19

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-4977-1
CVE-2020-25670, CVE-2020-25671, CVE-2020-25672, CVE-2020-25673,
CVE-2021-29155, CVE-2021-3501

Package Information:
  https://launchpad.net/ubuntu/+source/linux/5.11.0-18.19
  https://launchpad.net/ubuntu/+source/linux-aws/5.11.0-1008.8
  https://launchpad.net/ubuntu/+source/linux-azure/5.11.0-1006.6
  https://launchpad.net/ubuntu/+source/linux-gcp/5.11.0-1008.9
  https://launchpad.net/ubuntu/+source/linux-kvm/5.11.0-1008.8
  https://launchpad.net/ubuntu/+source/linux-oracle/5.11.0-1007.7