==========================================================================
Ubuntu Security Notice USN-4916-1
April 15, 2021

linux, linux-aws, linux-aws-hwe, linux-azure, linux-azure-4.15,
linux-dell300x, linux-gcp, linux-gcp-4.15, linux-hwe, linux-kvm,
linux-lts-xenial, linux-oracle, linux-raspi2, linux-snapdragon
vulnerabilities
==========================================================================

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

- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 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-azure-4.15: Linux kernel for Microsoft Azure Cloud systems
- linux-dell300x: Linux kernel for Dell 300x platforms
- linux-gcp-4.15: Linux kernel for Google Cloud Platform (GCP) systems
- linux-kvm: Linux kernel for cloud environments
- linux-oracle: Linux kernel for Oracle Cloud systems
- linux-raspi2: Linux kernel for Raspberry Pi (V8) systems
- linux-snapdragon: Linux kernel for Qualcomm Snapdragon processors
- linux-aws-hwe: Linux kernel for Amazon Web Services (AWS-HWE) systems
- linux-azure: Linux kernel for Microsoft Azure Cloud systems
- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems
- linux-hwe: Linux hardware enablement (HWE) kernel
- linux-lts-xenial: Linux hardware enablement kernel from Xenial for Trusty

Details:

It was discovered that the overlayfs implementation in the Linux kernel did
not properly validate the application of file system capabilities with
respect to user namespaces. A local attacker could use this to gain
elevated privileges. (CVE-2021-3493)

Piotr Krysiuk discovered that the BPF JIT compiler for x86 in the Linux
kernel did not properly validate computation of branch displacements in
some situations. A local attacker could use this to cause a denial of
service (system crash) or possibly execute arbitrary code. (CVE-2021-29154)

Update instructions:

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

Ubuntu 18.04 LTS:
  linux-image-4.15.0-1017-dell300x  4.15.0-1017.21
  linux-image-4.15.0-1070-oracle  4.15.0-1070.78
  linux-image-4.15.0-1084-raspi2  4.15.0-1084.89
  linux-image-4.15.0-1090-kvm     4.15.0-1090.92
  linux-image-4.15.0-1098-gcp     4.15.0-1098.111
  linux-image-4.15.0-1099-aws     4.15.0-1099.106
  linux-image-4.15.0-1101-snapdragon  4.15.0-1101.110
  linux-image-4.15.0-1113-azure   4.15.0-1113.126
  linux-image-4.15.0-142-generic  4.15.0-142.146
  linux-image-4.15.0-142-generic-lpae  4.15.0-142.146
  linux-image-4.15.0-142-lowlatency  4.15.0-142.146
  linux-image-aws-lts-18.04       4.15.0.1099.102
  linux-image-azure-lts-18.04     4.15.0.1113.86
  linux-image-dell300x            4.15.0.1017.19
  linux-image-gcp-lts-18.04       4.15.0.1098.116
  linux-image-generic             4.15.0.142.129
  linux-image-generic-lpae        4.15.0.142.129
  linux-image-kvm                 4.15.0.1090.86
  linux-image-lowlatency          4.15.0.142.129
  linux-image-oracle-lts-18.04    4.15.0.1070.80
  linux-image-powerpc-e500mc      4.15.0.142.129
  linux-image-powerpc-smp         4.15.0.142.129
  linux-image-powerpc64-emb       4.15.0.142.129
  linux-image-powerpc64-smp       4.15.0.142.129
  linux-image-raspi2              4.15.0.1084.81
  linux-image-snapdragon          4.15.0.1101.104
  linux-image-virtual             4.15.0.142.129

Ubuntu 16.04 LTS:
  linux-image-4.15.0-1070-oracle  4.15.0-1070.78~16.04.1
  linux-image-4.15.0-1098-gcp     4.15.0-1098.111~16.04.1
  linux-image-4.15.0-1099-aws     4.15.0-1099.106~16.04.1
  linux-image-4.15.0-1113-azure   4.15.0-1113.126~16.04.1
  linux-image-4.15.0-142-generic  4.15.0-142.146~16.04.1
  linux-image-4.15.0-142-generic-lpae  4.15.0-142.146~16.04.1
  linux-image-4.15.0-142-lowlatency  4.15.0-142.146~16.04.1
  linux-image-4.4.0-1092-kvm      4.4.0-1092.101
  linux-image-4.4.0-1127-aws      4.4.0-1127.141
  linux-image-4.4.0-1151-raspi2   4.4.0-1151.162
  linux-image-4.4.0-1155-snapdragon  4.4.0-1155.165
  linux-image-4.4.0-209-generic   4.4.0-209.241
  linux-image-4.4.0-209-generic-lpae  4.4.0-209.241
  linux-image-4.4.0-209-lowlatency  4.4.0-209.241
  linux-image-4.4.0-209-powerpc-e500mc  4.4.0-209.241
  linux-image-4.4.0-209-powerpc-smp  4.4.0-209.241
  linux-image-4.4.0-209-powerpc64-emb  4.4.0-209.241
  linux-image-4.4.0-209-powerpc64-smp  4.4.0-209.241
  linux-image-aws                 4.4.0.1127.132
  linux-image-aws-hwe             4.15.0.1099.92
  linux-image-azure               4.15.0.1113.104
  linux-image-gcp                 4.15.0.1098.99
  linux-image-generic             4.4.0.209.215
  linux-image-generic-hwe-16.04   4.15.0.142.137
  linux-image-generic-lpae        4.4.0.209.215
  linux-image-generic-lpae-hwe-16.04  4.15.0.142.137
  linux-image-gke                 4.15.0.1098.99
  linux-image-kvm                 4.4.0.1092.90
  linux-image-lowlatency          4.4.0.209.215
  linux-image-lowlatency-hwe-16.04  4.15.0.142.137
  linux-image-oem                 4.15.0.142.137
  linux-image-oracle              4.15.0.1070.58
  linux-image-powerpc-e500mc      4.4.0.209.215
  linux-image-powerpc-smp         4.4.0.209.215
  linux-image-powerpc64-emb       4.4.0.209.215
  linux-image-powerpc64-smp       4.4.0.209.215
  linux-image-raspi2              4.4.0.1151.151
  linux-image-snapdragon          4.4.0.1155.147
  linux-image-virtual             4.4.0.209.215
  linux-image-virtual-hwe-16.04   4.15.0.142.137

Ubuntu 14.04 ESM:
  linux-image-4.15.0-1113-azure   4.15.0-1113.126~14.04.1
  linux-image-4.4.0-1091-aws      4.4.0-1091.95
  linux-image-4.4.0-209-generic   4.4.0-209.241~14.04.1
  linux-image-4.4.0-209-generic-lpae  4.4.0-209.241~14.04.1
  linux-image-4.4.0-209-lowlatency  4.4.0-209.241~14.04.1
  linux-image-4.4.0-209-powerpc-e500mc  4.4.0-209.241~14.04.1
  linux-image-4.4.0-209-powerpc-smp  4.4.0-209.241~14.04.1
  linux-image-4.4.0-209-powerpc64-emb  4.4.0-209.241~14.04.1
  linux-image-4.4.0-209-powerpc64-smp  4.4.0-209.241~14.04.1
  linux-image-aws                 4.4.0.1091.88
  linux-image-azure               4.15.0.1113.86
  linux-image-generic-lpae-lts-xenial  4.4.0.209.182
  linux-image-generic-lts-xenial  4.4.0.209.182
  linux-image-lowlatency-lts-xenial  4.4.0.209.182
  linux-image-powerpc-e500mc-lts-xenial  4.4.0.209.182
  linux-image-powerpc-smp-lts-xenial  4.4.0.209.182
  linux-image-powerpc64-emb-lts-xenial  4.4.0.209.182
  linux-image-powerpc64-smp-lts-xenial  4.4.0.209.182
  linux-image-virtual-lts-xenial  4.4.0.209.182

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-4916-1
  CVE-2021-29154, CVE-2021-3493

Package Information:
  https://launchpad.net/ubuntu/+source/linux/4.15.0-142.146
  https://launchpad.net/ubuntu/+source/linux-aws/4.15.0-1099.106
  https://launchpad.net/ubuntu/+source/linux-azure-4.15/4.15.0-1113.126
  https://launchpad.net/ubuntu/+source/linux-dell300x/4.15.0-1017.21
  https://launchpad.net/ubuntu/+source/linux-gcp-4.15/4.15.0-1098.111
  https://launchpad.net/ubuntu/+source/linux-kvm/4.15.0-1090.92
  https://launchpad.net/ubuntu/+source/linux-oracle/4.15.0-1070.78
  https://launchpad.net/ubuntu/+source/linux-raspi2/4.15.0-1084.89
  https://launchpad.net/ubuntu/+source/linux-snapdragon/4.15.0-1101.110
  https://launchpad.net/ubuntu/+source/linux/4.4.0-209.241
  https://launchpad.net/ubuntu/+source/linux-aws/4.4.0-1127.141
  https://launchpad.net/ubuntu/+source/linux-aws-hwe/4.15.0-1099.106~16.04.1
  https://launchpad.net/ubuntu/+source/linux-azure/4.15.0-1113.126~16.04.1
  https://launchpad.net/ubuntu/+source/linux-gcp/4.15.0-1098.111~16.04.1
  https://launchpad.net/ubuntu/+source/linux-hwe/4.15.0-142.146~16.04.1
  https://launchpad.net/ubuntu/+source/linux-kvm/4.4.0-1092.101
  https://launchpad.net/ubuntu/+source/linux-oracle/4.15.0-1070.78~16.04.1
  https://launchpad.net/ubuntu/+source/linux-raspi2/4.4.0-1151.162
  https://launchpad.net/ubuntu/+source/linux-snapdragon/4.4.0-1155.165