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

USN-5017-1: Linux kernel vulnerabilities

=========================================================================
Ubuntu Security Notice USN-5017-1
July 20, 2021

linux, linux-aws, linux-aws-5.4, linux-azure, linux-azure-5.4, linux-gcp,
linux-gcp-5.4, linux-gke, linux-gke-5.4, linux-gkeop, linux-gkeop-5.4,
linux-hwe-5.4, linux-kvm, linux-oracle, linux-oracle-5.4, linux-raspi,
linux-raspi-5.4 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-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-gke: Linux kernel for Google Container Engine (GKE) systems
- linux-gkeop: Linux kernel for Google Container Engine (GKE) systems
- linux-kvm: Linux kernel for cloud environments
- linux-oracle: Linux kernel for Oracle Cloud systems
- linux-raspi: Linux kernel for Raspberry Pi (V8) systems
- linux-aws-5.4: Linux kernel for Amazon Web Services (AWS) systems
- linux-azure-5.4: Linux kernel for Microsoft Azure cloud systems
- linux-gcp-5.4: Linux kernel for Google Cloud Platform (GCP) systems
- linux-gke-5.4: Linux kernel for Google Container Engine (GKE) systems
- linux-gkeop-5.4: Linux kernel for Google Container Engine (GKE) systems
- linux-hwe-5.4: Linux hardware enablement (HWE) kernel
- linux-oracle-5.4: Linux kernel for Oracle Cloud systems
- linux-raspi-5.4: Linux kernel for Raspberry Pi (V8) systems

Details:

It was discovered that the virtual file system implementation in the Linux
kernel contained an unsigned to signed integer conversion error. A local
attacker could use this to cause a denial of service (system crash) or
execute arbitrary code. (CVE-2021-33909)

It was discovered that the bluetooth subsystem in the Linux kernel did not
properly perform access control. An authenticated attacker could possibly
use this to expose sensitive information. (CVE-2020-26558, CVE-2021-0129)

Update instructions:

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

Ubuntu 20.04 LTS:
linux-image-5.4.0-1021-gkeop 5.4.0-1021.22
linux-image-5.4.0-1041-raspi 5.4.0-1041.45
linux-image-5.4.0-1044-kvm 5.4.0-1044.46
linux-image-5.4.0-1049-gcp 5.4.0-1049.53
linux-image-5.4.0-1049-gke 5.4.0-1049.52
linux-image-5.4.0-1052-oracle 5.4.0-1052.56
linux-image-5.4.0-1054-aws 5.4.0-1054.57
linux-image-5.4.0-1055-azure 5.4.0-1055.57
linux-image-5.4.0-80-generic 5.4.0-80.90
linux-image-5.4.0-80-generic-lpae 5.4.0-80.90
linux-image-5.4.0-80-lowlatency 5.4.0-80.90
linux-image-aws-lts-20.04 5.4.0.1054.57
linux-image-azure-lts-20.04 5.4.0.1055.53
linux-image-gcp-lts-20.04 5.4.0.1049.59
linux-image-generic 5.4.0.80.84
linux-image-generic-lpae 5.4.0.80.84
linux-image-gke 5.4.0.1049.59
linux-image-gke-5.4 5.4.0.1049.59
linux-image-gkeop 5.4.0.1021.24
linux-image-gkeop-5.4 5.4.0.1021.24
linux-image-kvm 5.4.0.1044.43
linux-image-lowlatency 5.4.0.80.84
linux-image-oem 5.4.0.80.84
linux-image-oem-osp1 5.4.0.80.84
linux-image-oracle-lts-20.04 5.4.0.1052.52
linux-image-raspi 5.4.0.1041.76
linux-image-raspi2 5.4.0.1041.76
linux-image-virtual 5.4.0.80.84

Ubuntu 18.04 LTS:
linux-image-5.4.0-1021-gkeop 5.4.0-1021.22~18.04.1
linux-image-5.4.0-1041-raspi 5.4.0-1041.45~18.04.1
linux-image-5.4.0-1049-gcp 5.4.0-1049.53~18.04.1
linux-image-5.4.0-1049-gke 5.4.0-1049.52~18.04.1
linux-image-5.4.0-1052-oracle 5.4.0-1052.56~18.04.1
linux-image-5.4.0-1054-aws 5.4.0-1054.57~18.04.1
linux-image-5.4.0-1055-azure 5.4.0-1055.57~18.04.1
linux-image-5.4.0-80-generic 5.4.0-80.90~18.04.1
linux-image-5.4.0-80-generic-lpae 5.4.0-80.90~18.04.1
linux-image-5.4.0-80-lowlatency 5.4.0-80.90~18.04.1
linux-image-aws 5.4.0.1054.37
linux-image-azure 5.4.0.1055.35
linux-image-gcp 5.4.0.1049.36
linux-image-generic-hwe-18.04 5.4.0.80.90~18.04.72
linux-image-generic-lpae-hwe-18.04 5.4.0.80.90~18.04.72
linux-image-gke-5.4 5.4.0.1049.52~18.04.15
linux-image-gkeop-5.4 5.4.0.1021.22~18.04.22
linux-image-lowlatency-hwe-18.04 5.4.0.80.90~18.04.72
linux-image-oem 5.4.0.80.90~18.04.72
linux-image-oem-osp1 5.4.0.80.90~18.04.72
linux-image-oracle 5.4.0.1052.56~18.04.32
linux-image-raspi-hwe-18.04 5.4.0.1041.44
linux-image-snapdragon-hwe-18.04 5.4.0.80.90~18.04.72
linux-image-virtual-hwe-18.04 5.4.0.80.90~18.04.72

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-5017-1
CVE-2020-26558, CVE-2021-0129, CVE-2021-33909

Package Information:
  https://launchpad.net/ubuntu/+source/linux/5.4.0-80.90
  https://launchpad.net/ubuntu/+source/linux-aws/5.4.0-1054.57
  https://launchpad.net/ubuntu/+source/linux-azure/5.4.0-1055.57
  https://launchpad.net/ubuntu/+source/linux-gcp/5.4.0-1049.53
  https://launchpad.net/ubuntu/+source/linux-gke/5.4.0-1049.52
  https://launchpad.net/ubuntu/+source/linux-gkeop/5.4.0-1021.22
  https://launchpad.net/ubuntu/+source/linux-kvm/5.4.0-1044.46
  https://launchpad.net/ubuntu/+source/linux-oracle/5.4.0-1052.56
  https://launchpad.net/ubuntu/+source/linux-raspi/5.4.0-1041.45
  https://launchpad.net/ubuntu/+source/linux-aws-5.4/5.4.0-1054.57~18.04.1
  https://launchpad.net/ubuntu/+source/linux-azure-5.4/5.4.0-1055.57~18.04.1
  https://launchpad.net/ubuntu/+source/linux-gcp-5.4/5.4.0-1049.53~18.04.1
  https://launchpad.net/ubuntu/+source/linux-gke-5.4/5.4.0-1049.52~18.04.1
  https://launchpad.net/ubuntu/+source/linux-gkeop-5.4/5.4.0-1021.22~18.04.1
  https://launchpad.net/ubuntu/+source/linux-hwe-5.4/5.4.0-80.90~18.04.1
  https://launchpad.net/ubuntu/+source/linux-oracle-5.4/5.4.0-1052.56~18.04.1
  https://launchpad.net/ubuntu/+source/linux-raspi-5.4/5.4.0-1041.45~18.04.1