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

USN-4411-1: Linux kernel vulnerabilities

=========================================================================
Ubuntu Security Notice USN-4411-1
July 02, 2020

linux, linux-aws, linux-gcp, linux-kvm, linux-oracle, linux-riscv
vulnerabilities
=========================================================================
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-aws: Linux kernel for Amazon Web Services (AWS) 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-riscv: Linux kernel for RISC-V systems

Details:

It was discovered that the elf handling code in the Linux kernel did not
initialize memory before using it in certain situations. A local attacker
could use this to possibly expose sensitive information (kernel memory).
(CVE-2020-10732)

Matthew Sheets discovered that the SELinux network label handling
implementation in the Linux kernel could be coerced into de-referencing a
NULL pointer. A remote attacker could use this to cause a denial of service
(system crash). (CVE-2020-10711)

It was discovered that the SCSI generic (sg) driver in the Linux kernel did
not properly handle certain error conditions correctly. A local privileged
attacker could use this to cause a denial of service (system crash).
(CVE-2020-12770)

It was discovered that the USB Gadget device driver in the Linux kernel did
not validate arguments passed from configfs in some situations. A local
attacker could possibly use this to cause a denial of service (system
crash) or possibly expose sensitive information. (CVE-2020-13143)

It was discovered that the KVM implementation in the Linux kernel did not
properly deallocate memory on initialization for some processors. A local
attacker could possibly use this to cause a denial of service.
(CVE-2020-12768)

Update instructions:

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

Ubuntu 20.04 LTS:
linux-image-5.4.0-1018-aws 5.4.0-1018.18
linux-image-5.4.0-1019-gcp 5.4.0-1019.19
linux-image-5.4.0-1019-oracle 5.4.0-1019.19
linux-image-5.4.0-28-generic 5.4.0-28.32
linux-image-5.4.0-40-generic 5.4.0-40.44
linux-image-5.4.0-40-generic-lpae 5.4.0-40.44
linux-image-5.4.0-40-lowlatency 5.4.0-40.44
linux-image-aws 5.4.0.1018.19
linux-image-gcp 5.4.0.1019.17
linux-image-generic 5.4.0.28.35
linux-image-generic-lpae 5.4.0.40.43
linux-image-gke 5.4.0.1019.17
linux-image-kvm 5.4.0.1018.17
linux-image-lowlatency 5.4.0.40.43
linux-image-oem 5.4.0.40.43
linux-image-oem-osp1 5.4.0.40.43
linux-image-oracle 5.4.0.1019.17
linux-image-virtual 5.4.0.28.35

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/4411-1
CVE-2020-10711, CVE-2020-10732, CVE-2020-12768, CVE-2020-12770,
CVE-2020-13143

Package Information:
  https://launchpad.net/ubuntu/+source/linux/5.4.0-40.44
  https://launchpad.net/ubuntu/+source/linux-aws/5.4.0-1018.18
  https://launchpad.net/ubuntu/+source/linux-gcp/5.4.0-1019.19
  https://launchpad.net/ubuntu/+source/linux-kvm/5.4.0-1018.18
  https://launchpad.net/ubuntu/+source/linux-oracle/5.4.0-1019.19
  https://launchpad.net/ubuntu/+source/linux-riscv/5.4.0-28.32