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

USN-4525-1: Linux kernel vulnerabilities

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Ubuntu Security Notice USN-4525-1
September 21, 2020

linux, linux-azure, linux-gcp, linux-oracle vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux: Linux kernel
- linux-azure: Linux kernel for Microsoft Azure Cloud systems
- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems
- linux-oracle: Linux kernel for Oracle Cloud systems

Details:

It was discovered that the AMD Cryptographic Coprocessor device driver in
the Linux kernel did not properly deallocate memory in some situations. A
local attacker could use this to cause a denial of service (memory
exhaustion). (CVE-2019-18808)

It was discovered that the Conexant 23885 TV card device driver for the
Linux kernel did not properly deallocate memory in some error conditions. A
local attacker could use this to cause a denial of service (memory
exhaustion). (CVE-2019-19054)

It was discovered that the VFIO PCI driver in the Linux kernel did not
properly handle attempts to access disabled memory spaces. A local attacker
could use this to cause a denial of service (system crash).
(CVE-2020-12888)

It was discovered that the state of network RNG in the Linux kernel was
potentially observable. A remote attacker could use this to expose
sensitive information. (CVE-2020-16166)

It was discovered that the NFS client implementation in the Linux kernel
did not properly perform bounds checking before copying security labels in
some situations. A local attacker could use this to cause a denial of
service (system crash) or possibly execute arbitrary code. (CVE-2020-25212)

Update instructions:

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

Ubuntu 20.04 LTS:
linux-image-5.4.0-1025-gcp 5.4.0-1025.25
linux-image-5.4.0-1025-oracle 5.4.0-1025.25
linux-image-5.4.0-1026-azure 5.4.0-1026.26
linux-image-5.4.0-48-generic 5.4.0-48.52
linux-image-5.4.0-48-generic-lpae 5.4.0-48.52
linux-image-5.4.0-48-lowlatency 5.4.0-48.52
linux-image-azure 5.4.0.1026.25
linux-image-gcp 5.4.0.1025.22
linux-image-generic 5.4.0.48.51
linux-image-generic-lpae 5.4.0.48.51
linux-image-gke 5.4.0.1025.22
linux-image-lowlatency 5.4.0.48.51
linux-image-oem 5.4.0.48.51
linux-image-oem-osp1 5.4.0.48.51
linux-image-oracle 5.4.0.1025.22
linux-image-virtual 5.4.0.48.51

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://usn.ubuntu.com/4525-1
CVE-2019-18808, CVE-2019-19054, CVE-2020-12888, CVE-2020-16166,
CVE-2020-25212

Package Information:
  https://launchpad.net/ubuntu/+source/linux/5.4.0-48.52
  https://launchpad.net/ubuntu/+source/linux-azure/5.4.0-1026.26
  https://launchpad.net/ubuntu/+source/linux-gcp/5.4.0-1025.25
  https://launchpad.net/ubuntu/+source/linux-oracle/5.4.0-1025.25