A Linux kernel security update has been released for Ubuntu Linux 14.04 ESM, 16.04 ESM, and 18.04 LTS.

USN-5073-1: Linux kernel vulnerabilities

=========================================================================
Ubuntu Security Notice USN-5073-1
September 09, 2021

linux, linux-aws, linux-aws-hwe, linux-azure, linux-azure-4.15,
linux-dell300x, linux-hwe, linux-kvm, linux-oracle, linux-snapdragon
vulnerabilities
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS
- Ubuntu 16.04 ESM
- 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-kvm: Linux kernel for cloud environments
- linux-oracle: Linux kernel for Oracle Cloud 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-hwe: Linux hardware enablement (HWE) kernel

Details:

Maxim Levitsky and Paolo Bonzini discovered that the KVM hypervisor
implementation for AMD processors in the Linux kernel allowed a guest VM to
disable restrictions on VMLOAD/VMSAVE in a nested guest. An attacker in a
guest VM could use this to read or write portions of the host's physical
memory. (CVE-2021-3656)

Maxim Levitsky discovered that the KVM hypervisor implementation for AMD
processors in the Linux kernel did not properly prevent a guest VM from
enabling AVIC in nested guest VMs. An attacker in a guest VM could use this
to write to portions of the host's physical memory. (CVE-2021-3653)

Norbert Slusarek discovered that the CAN broadcast manger (bcm) protocol
implementation in the Linux kernel did not properly initialize memory in
some situations. A local attacker could use this to expose sensitive
information (kernel memory). (CVE-2021-34693)

Murray McAllister discovered that the joystick device interface in the
Linux kernel did not properly validate data passed via an ioctl(). A local
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code on systems with a joystick device
registered. (CVE-2021-3612)

It was discovered that the Virtio console implementation in the Linux
kernel did not properly validate input lengths in some situations. A local
attacker could possibly use this to cause a denial of service (system
crash). (CVE-2021-38160)

Update instructions:

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

Ubuntu 18.04 LTS:
linux-image-4.15.0-1027-dell300x 4.15.0-1027.32
linux-image-4.15.0-1080-oracle 4.15.0-1080.88
linux-image-4.15.0-1099-kvm 4.15.0-1099.101
linux-image-4.15.0-1111-aws 4.15.0-1111.118
linux-image-4.15.0-1112-snapdragon 4.15.0-1112.121
linux-image-4.15.0-1123-azure 4.15.0-1123.136
linux-image-4.15.0-156-generic 4.15.0-156.163
linux-image-4.15.0-156-generic-lpae 4.15.0-156.163
linux-image-4.15.0-156-lowlatency 4.15.0-156.163
linux-image-aws-lts-18.04 4.15.0.1111.114
linux-image-azure-lts-18.04 4.15.0.1123.96
linux-image-dell300x 4.15.0.1027.29
linux-image-generic 4.15.0.156.145
linux-image-generic-lpae 4.15.0.156.145
linux-image-kvm 4.15.0.1099.95
linux-image-lowlatency 4.15.0.156.145
linux-image-oracle-lts-18.04 4.15.0.1080.90
linux-image-snapdragon 4.15.0.1112.115
linux-image-virtual 4.15.0.156.145

Ubuntu 16.04 ESM:
linux-image-4.15.0-1080-oracle 4.15.0-1080.88~16.04.1
linux-image-4.15.0-1111-aws 4.15.0-1111.118~16.04.1
linux-image-4.15.0-1123-azure 4.15.0-1123.136~16.04.1
linux-image-4.15.0-156-generic 4.15.0-156.163~16.04.1
linux-image-4.15.0-156-lowlatency 4.15.0-156.163~16.04.1
linux-image-aws-hwe 4.15.0.1111.102
linux-image-azure 4.15.0.1123.114
linux-image-generic-hwe-16.04 4.15.0.156.149
linux-image-lowlatency-hwe-16.04 4.15.0.156.149
linux-image-oem 4.15.0.156.149
linux-image-oracle 4.15.0.1080.68
linux-image-virtual-hwe-16.04 4.15.0.156.149

Ubuntu 14.04 ESM:
linux-image-4.15.0-1123-azure 4.15.0-1123.136~14.04.1
linux-image-azure 4.15.0.1123.96

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-5073-1
CVE-2021-34693, CVE-2021-3612, CVE-2021-3653, CVE-2021-3656,
CVE-2021-38160

Package Information:
  https://launchpad.net/ubuntu/+source/linux/4.15.0-156.163
  https://launchpad.net/ubuntu/+source/linux-aws/4.15.0-1111.118
  https://launchpad.net/ubuntu/+source/linux-azure-4.15/4.15.0-1123.136
  https://launchpad.net/ubuntu/+source/linux-dell300x/4.15.0-1027.32
  https://launchpad.net/ubuntu/+source/linux-kvm/4.15.0-1099.101
  https://launchpad.net/ubuntu/+source/linux-oracle/4.15.0-1080.88
  https://launchpad.net/ubuntu/+source/linux-snapdragon/4.15.0-1112.121