1. Ubuntu Security Notices
  2. USN-5094-1

USN-5094-1: Linux kernel vulnerabilities

Publication date

29 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-hwe - Linux kernel for Amazon Web Services (AWS-HWE) systems
  • linux-azure - Linux kernel for Microsoft Azure Cloud systems
  • linux-azure-4.15 - Linux kernel for Microsoft Azure Cloud systems
  • linux-dell300x - Linux kernel for Dell 300x platforms
  • linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
  • linux-gcp-4.15 - Linux kernel for Google Cloud Platform (GCP) systems
  • linux-hwe - Linux hardware enablement (HWE) kernel
  • linux-kvm - Linux kernel for cloud environments
  • linux-oracle - Linux kernel for Oracle Cloud systems
  • linux-snapdragon - Linux kernel for Qualcomm Snapdragon processors

Details

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)

It was discovered that the tracing subsystem in the Linux kernel did not
properly keep track of per-cpu ring buffer state. A privileged attacker
could use this to cause a denial of service. (CVE-2021-3679)

Alois Wohlschlager discovered that the overlay file system in the Linux
kernel did not restrict private clones in some situations. An attacker
could use this to expose sensitive information. (CVE-2021-3732)

Alexey Kardashevskiy discovered that the KVM implementation for PowerPC
systems...

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)

It was discovered that the tracing subsystem in the Linux kernel did not
properly keep track of per-cpu ring buffer state. A privileged attacker
could use this to cause a denial of service. (CVE-2021-3679)

Alois Wohlschlager discovered that the overlay file system in the Linux
kernel did not restrict private clones in some situations. An attacker
could use this to expose sensitive information. (CVE-2021-3732)

Alexey Kardashevskiy discovered that the KVM implementation for PowerPC
systems in the Linux kernel did not properly validate RTAS arguments in
some situations. An attacker in a guest vm could use this to cause a denial
of service (host OS crash) or possibly execute arbitrary code.
(CVE-2021-37576)

It was discovered that the MAX-3421 host USB device driver in the Linux
kernel did not properly handle device removal events. A physically
proximate attacker could use this to cause a denial of service (system
crash). (CVE-2021-38204)

It was discovered that the Xilinx 10/100 Ethernet Lite device driver in the
Linux kernel could report pointer addresses in some situations. An attacker
could use this information to ease the exploitation of another
vulnerability. (CVE-2021-38205)

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
18.04 bionic linux-image-4.15.0-1028-dell300x –  4.15.0-1028.33
linux-image-4.15.0-1081-oracle –  4.15.0-1081.89
linux-image-4.15.0-1100-kvm –  4.15.0-1100.102
linux-image-4.15.0-1109-gcp –  4.15.0-1109.123
linux-image-4.15.0-1112-aws –  4.15.0-1112.119
linux-image-4.15.0-1113-snapdragon –  4.15.0-1113.122
linux-image-4.15.0-1124-azure –  4.15.0-1124.137
linux-image-4.15.0-159-generic –  4.15.0-159.167
linux-image-4.15.0-159-generic-lpae –  4.15.0-159.167
linux-image-4.15.0-159-lowlatency –  4.15.0-159.167
linux-image-aws-lts-18.04 –  4.15.0.1112.115
linux-image-azure-lts-18.04 –  4.15.0.1124.97
linux-image-dell300x –  4.15.0.1028.30
linux-image-gcp-lts-18.04 –  4.15.0.1109.128
linux-image-generic –  4.15.0.159.148
linux-image-generic-lpae –  4.15.0.159.148
linux-image-kvm –  4.15.0.1100.96
linux-image-lowlatency –  4.15.0.159.148
linux-image-oracle-lts-18.04 –  4.15.0.1081.91
linux-image-snapdragon –  4.15.0.1113.116
linux-image-virtual –  4.15.0.159.148
16.04 xenial linux-image-4.15.0-1081-oracle –  4.15.0-1081.89~16.04.1  
linux-image-4.15.0-1109-gcp –  4.15.0-1109.123~16.04.1  
linux-image-4.15.0-1112-aws –  4.15.0-1112.119~16.04.1  
linux-image-4.15.0-1124-azure –  4.15.0-1124.137~16.04.1  
linux-image-4.15.0-159-generic –  4.15.0-159.167~16.04.1  
linux-image-4.15.0-159-lowlatency –  4.15.0-159.167~16.04.1  
linux-image-aws-hwe –  4.15.0.1112.103  
linux-image-azure –  4.15.0.1124.115  
linux-image-gcp –  4.15.0.1109.110  
linux-image-generic-hwe-16.04 –  4.15.0.159.152  
linux-image-gke –  4.15.0.1109.110  
linux-image-lowlatency-hwe-16.04 –  4.15.0.159.152  
linux-image-oem –  4.15.0.159.152  
linux-image-oracle –  4.15.0.1081.69  
linux-image-virtual-hwe-16.04 –  4.15.0.159.152  
14.04 trusty linux-image-4.15.0-1124-azure –  4.15.0-1124.137~14.04.1  
linux-image-azure –  4.15.0.1124.97  

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References

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