USN-4367-1: Linux kernel vulnerabilities

24 May 2020

linux, linux-aws, linux-azure, linux-gcp, linux-kvm, linux-oracle, linux-raspi, linux-riscv vulnerabilities

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

  • Ubuntu 20.04 LTS


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 - Linux kernel for Microsoft Azure Cloud 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-raspi - Linux kernel for Raspberry Pi (V8) systems
  • linux-riscv - Linux kernel for RISC-V systems


It was discovered that the btrfs implementation in the Linux kernel did not properly detect that a block was marked dirty in some situations. An attacker could use this to specially craft a file system image that, when unmounted, could cause a denial of service (system crash). (CVE-2019-19377)

It was discovered that the linux kernel did not properly validate certain mount options to the tmpfs virtual memory file system. A local attacker with the ability to specify mount options could use this to cause a denial of service (system crash). (CVE-2020-11565)

It was discovered that the block layer in the Linux kernel contained a race condition leading to a use-after-free vulnerability. A local attacker could possibly use this to cause a denial of service (system crash) or execute arbitrary code. (CVE-2020-12657)

Update instructions

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

Ubuntu 20.04 LTS
linux-image-5.4.0-1011-aws - 5.4.0-1011.11
linux-image-5.4.0-1011-gcp - 5.4.0-1011.11
linux-image-5.4.0-1011-kvm - 5.4.0-1011.11
linux-image-5.4.0-1011-oracle - 5.4.0-1011.11
linux-image-5.4.0-1011-raspi - 5.4.0-1011.11
linux-image-5.4.0-1012-azure - 5.4.0-1012.12
linux-image-5.4.0-26-generic - 5.4.0-26.30
linux-image-5.4.0-31-generic - 5.4.0-31.35
linux-image-5.4.0-31-generic-lpae - 5.4.0-31.35
linux-image-5.4.0-31-lowlatency - 5.4.0-31.35
linux-image-aws -
linux-image-azure -
linux-image-gcp -
linux-image-generic -
linux-image-generic-lpae -
linux-image-gke -
linux-image-kvm -
linux-image-lowlatency -
linux-image-oem -
linux-image-oem-osp1 -
linux-image-oracle -
linux-image-raspi -
linux-image-raspi2 -
linux-image-virtual -

To update your system, please follow these instructions:

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.