1. Ubuntu Security Notices
  2. USN-5071-1

USN-5071-1: Linux kernel vulnerabilities

Publication date

8 September 2021

Overview

Several security issues were fixed in the Linux kernel.

Releases

Packages

  • linux - Linux kernel
  • linux-aws - Linux kernel for Amazon Web Services (AWS) systems
  • linux-aws-5.4 - Linux kernel for Amazon Web Services (AWS) systems
  • linux-azure - Linux kernel for Microsoft Azure Cloud systems
  • linux-azure-5.4 - Linux kernel for Microsoft Azure cloud systems
  • linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
  • linux-gcp-5.4 - Linux kernel for Google Cloud Platform (GCP) systems
  • linux-gke - Linux kernel for Google Container Engine (GKE) systems
  • linux-gke-5.4 - Linux kernel for Google Container Engine (GKE) systems
  • linux-gkeop - Linux kernel for Google Container Engine (GKE) systems
  • linux-gkeop-5.4 - Linux kernel for Google Container Engine (GKE) systems
  • linux-kvm - Linux kernel for cloud environments
  • linux-oracle - Linux kernel for Oracle Cloud systems
  • linux-oracle-5.4 - Linux kernel for Oracle Cloud systems

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)

It was discovered that the KVM hypervisor implementation for AMD processors
in the Linux kernel did not ensure enough processing time was given to
perform cleanups of large SEV VMs. A local attacker could use this to cause
a denial of service (soft lockup)....

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)

It was discovered that the KVM hypervisor implementation for AMD processors
in the Linux kernel did not ensure enough processing time was given to
perform cleanups of large SEV VMs. A local attacker could use this to cause
a denial of service (soft lockup). (CVE-2020-36311)

It was discovered that the KVM hypervisor implementation in the Linux
kernel did not properly perform reference counting in some situations,
leading to a use-after-free vulnerability. An attacker who could start and
control a VM could possibly use this to expose sensitive information or
execute arbitrary code. (CVE-2021-22543)

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)

Update instructions

After a standard system update you need to reboot your computer to make all the necessary changes.

Learn more about how to get the fixes.

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.

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

Ubuntu Release Package Version
20.04 focal linux-image-5.4.0-1052-gke –  5.4.0-1052.55
linux-image-5.4.0-84-generic-lpae –  5.4.0-84.94
linux-image-5.4.0-1052-gcp –  5.4.0-1052.56
linux-image-gkeop –  5.4.0.1023.26
linux-image-virtual –  5.4.0.84.88
linux-image-generic –  5.4.0.84.88
linux-image-5.4.0-84-generic –  5.4.0-84.94
linux-image-5.4.0-1023-gkeop –  5.4.0-1023.24
linux-image-oem-osp1 –  5.4.0.84.88
linux-image-5.4.0-1046-kvm –  5.4.0-1046.48
linux-image-azure-lts-20.04 –  5.4.0.1058.56
linux-image-5.4.0-1058-azure –  5.4.0-1058.60
linux-image-gkeop-5.4 –  5.4.0.1023.26
linux-image-5.4.0-1054-oracle –  5.4.0-1054.58
linux-image-gcp-lts-20.04 –  5.4.0.1052.62
linux-image-aws-lts-20.04 –  5.4.0.1056.59
linux-image-5.4.0-1056-aws –  5.4.0-1056.59
linux-image-5.4.0-84-lowlatency –  5.4.0-84.94
linux-image-gke –  5.4.0.1052.62
linux-image-oracle-lts-20.04 –  5.4.0.1054.54
linux-image-gke-5.4 –  5.4.0.1052.62
linux-image-kvm –  5.4.0.1046.45
linux-image-oem –  5.4.0.84.88
linux-image-generic-lpae –  5.4.0.84.88
linux-image-lowlatency –  5.4.0.84.88
18.04 bionic linux-image-5.4.0-1052-gke –  5.4.0-1052.55~18.04.1
linux-image-5.4.0-1052-gcp –  5.4.0-1052.56~18.04.1
linux-image-5.4.0-1023-gkeop –  5.4.0-1023.24~18.04.1
linux-image-aws –  5.4.0.1056.39
linux-image-5.4.0-1058-azure –  5.4.0-1058.60~18.04.1
linux-image-gkeop-5.4 –  5.4.0.1023.24~18.04.24
linux-image-5.4.0-1054-oracle –  5.4.0-1054.58~18.04.1
linux-image-azure –  5.4.0.1058.38
linux-image-5.4.0-1056-aws –  5.4.0-1056.59~18.04.1
linux-image-gcp –  5.4.0.1052.38
linux-image-oracle –  5.4.0.1054.58~18.04.34
linux-image-gke-5.4 –  5.4.0.1052.55~18.04.17

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References

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