A Linux kernel security update has been released for Ubuntu Linux 18.04 LTS and 20.04 LTS.

LSN-0077-1: Linux kernel vulnerability

Linux kernel vulnerabilities

A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary

Several security issues were fixed in the kernel.

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-gke - Linux kernel for Google Container Engine (GKE) systems - linux-gkeop - Linux kernel for Google Container Engine (GKE) systems

Details

Vincent Dehors discovered that the shiftfs file system in the Ubuntu Linux kernel did not properly handle faults in copy_from_user() when passing through ioctls to an underlying file system. A local attacker could use this to cause a denial of service (memory exhaustion) or execute arbitrary code. (CVE-2021-3492)

Update instructions

The problem can be corrected by updating your kernel livepatch to the following versions:

Ubuntu 20.04 LTS
aws - 77.1
azure - 77.1
gcp - 77.1
generic - 77.1
gke - 77.1
gkeop - 77.1
lowlatency - 77.1

Ubuntu 18.04 LTS
generic - 77.1
gke - 77.1
gkeop - 77.1
lowlatency - 77.1

Support Information

Kernels older than the levels listed below do not receive livepatch updates. If you are running a kernel version earlier than the one listed
below, please upgrade your kernel as soon as possible.

Ubuntu 20.04 LTS
linux-aws - 5.4.0-1009
linux-azure - 5.4.0-1010
linux-gcp - 5.4.0-1009
linux-gke - 5.4.0-1033
linux-gkeop - 5.4.0-1009
linux-oem - 5.4.0-26
linux - 5.4.0-26

Ubuntu 18.04 LTS
linux-aws-fips - 4.15.0-2030
linux-aws - 4.15.0-1054
linux-azure-fips - 4.15.0-2012
linux-fips - 4.15.0-1045
linux-gke-4.15 - 4.15.0-1076
linux-gke-5.4 - 5.4.0-1009
linux-gkeop-5.4 - 5.4.0-1007
linux-hwe-5.4 - 5.4.0-26
linux-oem - 4.15.0-1063
linux - 4.15.0-69

Ubuntu 16.04 LTS
linux-aws - 4.4.0-1098
linux-azure - 4.15.0-1063
linux-azure - 4.15.0-1078
linux-fips - 4.4.0-1049
linux-hwe - 4.15.0-69
linux - 4.4.0-168

Ubuntu 14.04 ESM
linux-lts-xenial - 4.4.0-168

References

- CVE-2021-3492