=========================================================================
Ubuntu Security Notice USN-5014-1
July 20, 2021

linux, linux-aws, linux-azure, linux-gcp, linux-gke-5.3, linux-hwe,
linux-lts-xenial, linux-kvm, linux-oracle, linux-raspi, linux-raspi2-5.3
vulnerability
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 21.04
- Ubuntu 18.04 LTS
- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

The system could be made to run programs as an administrator.

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
- linux-raspi: Linux kernel for Raspberry Pi (V8) systems
- linux-gke-5.3: Linux kernel for Google Container Engine (GKE) systems
- linux-hwe: Linux hardware enablement (HWE) kernel
- linux-raspi2-5.3: Linux kernel for Raspberry Pi (V8) systems
- linux-lts-xenial: Linux hardware enablement kernel from Xenial for Trusty

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.

Update instructions:

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

Ubuntu 21.04:
  linux-image-5.11.0-1012-azure   5.11.0-1012.13
  linux-image-5.11.0-1012-kvm     5.11.0-1012.13
  linux-image-5.11.0-1013-oracle  5.11.0-1013.14
  linux-image-5.11.0-1014-aws     5.11.0-1014.15
  linux-image-5.11.0-1014-gcp     5.11.0-1014.16
  linux-image-5.11.0-1015-raspi   5.11.0-1015.16
  linux-image-5.11.0-1015-raspi-nolpae  5.11.0-1015.16
  linux-image-5.11.0-25-generic   5.11.0-25.27
  linux-image-5.11.0-25-generic-64k  5.11.0-25.27
  linux-image-5.11.0-25-generic-lpae  5.11.0-25.27
  linux-image-5.11.0-25-lowlatency  5.11.0-25.27
  linux-image-aws                 5.11.0.1014.15
  linux-image-azure               5.11.0.1012.13
  linux-image-gcp                 5.11.0.1014.14
  linux-image-generic             5.11.0.25.27
  linux-image-generic-64k         5.11.0.25.27
  linux-image-generic-lpae        5.11.0.25.27
  linux-image-gke                 5.11.0.1014.14
  linux-image-kvm                 5.11.0.1012.13
  linux-image-lowlatency          5.11.0.25.27
  linux-image-oem-20.04           5.11.0.25.27
  linux-image-oracle              5.11.0.1013.14
  linux-image-raspi               5.11.0.1015.13
  linux-image-raspi-nolpae        5.11.0.1015.13
  linux-image-virtual             5.11.0.25.27

Ubuntu 18.04 LTS:
  linux-image-5.3.0-1042-raspi2   5.3.0-1042.44
  linux-image-5.3.0-1045-gke      5.3.0-1045.48
  linux-image-5.3.0-76-generic    5.3.0-76.72
  linux-image-5.3.0-76-lowlatency  5.3.0-76.72
  linux-image-gke-5.3             5.3.0.1045.28
  linux-image-gkeop-5.3           5.3.0.76.133
  linux-image-raspi2-hwe-18.04    5.3.0.1042.31

Ubuntu 16.04 ESM:
  linux-image-4.4.0-1095-kvm      4.4.0-1095.104
  linux-image-4.4.0-1130-aws      4.4.0-1130.144
  linux-image-4.4.0-212-generic   4.4.0-212.244
  linux-image-4.4.0-212-lowlatency  4.4.0-212.244
  linux-image-aws                 4.4.0.1130.135
  linux-image-generic             4.4.0.212.219
  linux-image-kvm                 4.4.0.1095.93
  linux-image-lowlatency          4.4.0.212.219
  linux-image-virtual             4.4.0.212.219

Ubuntu 14.04 ESM:
  linux-image-3.13.0-186-generic  3.13.0-186.237
  linux-image-3.13.0-186-generic-lpae  3.13.0-186.237
  linux-image-3.13.0-186-lowlatency  3.13.0-186.237
  linux-image-3.13.0-186-powerpc-e500  3.13.0-186.237
  linux-image-3.13.0-186-powerpc-e500mc  3.13.0-186.237
  linux-image-3.13.0-186-powerpc-smp  3.13.0-186.237
  linux-image-3.13.0-186-powerpc64-emb  3.13.0-186.237
  linux-image-3.13.0-186-powerpc64-smp  3.13.0-186.237
  linux-image-4.4.0-1094-aws      4.4.0-1094.99
  linux-image-4.4.0-212-generic   4.4.0-212.244~14.04.1
  linux-image-4.4.0-212-lowlatency  4.4.0-212.244~14.04.1
  linux-image-aws                 4.4.0.1094.92
  linux-image-generic             3.13.0.186.195
  linux-image-generic-lpae        3.13.0.186.195
  linux-image-generic-lts-xenial  4.4.0.212.185
  linux-image-generic-pae         3.13.0.186.195
  linux-image-highbank            3.13.0.186.195
  linux-image-lowlatency          3.13.0.186.195
  linux-image-lowlatency-lts-xenial  4.4.0.212.185
  linux-image-lowlatency-pae      3.13.0.186.195
  linux-image-omap                3.13.0.186.195
  linux-image-powerpc-e500        3.13.0.186.195
  linux-image-powerpc-e500mc      3.13.0.186.195
  linux-image-powerpc-smp         3.13.0.186.195
  linux-image-powerpc64-emb       3.13.0.186.195
  linux-image-powerpc64-smp       3.13.0.186.195
  linux-image-server              3.13.0.186.195
  linux-image-virtual             3.13.0.186.195
  linux-image-virtual-lts-xenial  4.4.0.212.185

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-5014-1
  CVE-2021-33909

Package Information:
  https://launchpad.net/ubuntu/+source/linux/5.11.0-25.27
  https://launchpad.net/ubuntu/+source/linux-aws/5.11.0-1014.15
  https://launchpad.net/ubuntu/+source/linux-azure/5.11.0-1012.13
  https://launchpad.net/ubuntu/+source/linux-gcp/5.11.0-1014.16
  https://launchpad.net/ubuntu/+source/linux-kvm/5.11.0-1012.13
  https://launchpad.net/ubuntu/+source/linux-oracle/5.11.0-1013.14
  https://launchpad.net/ubuntu/+source/linux-raspi/5.11.0-1015.16
  https://launchpad.net/ubuntu/+source/linux-gke-5.3/5.3.0-1045.48
  https://launchpad.net/ubuntu/+source/linux-hwe/5.3.0-76.72
  https://launchpad.net/ubuntu/+source/linux-raspi2-5.3/5.3.0-1042.44