1. Ubuntu Security Notices
  2. USN-4426-1

USN-4426-1: Linux kernel vulnerabilities

Publication date

27 July 2020

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-gcp - Linux kernel for Google Cloud Platform (GCP) systems
  • linux-gcp-4.15 - Linux kernel for Google Cloud Platform (GCP) systems
  • linux-gke-4.15 - Linux kernel for Google Container Engine (GKE) systems
  • linux-hwe - Linux hardware enablement (HWE) kernel
  • linux-kvm - Linux kernel for cloud environments
  • linux-oem - Linux kernel for OEM systems
  • linux-oracle - Linux kernel for Oracle Cloud systems
  • linux-raspi2 - Linux kernel for Raspberry Pi (V7) systems
  • linux-snapdragon - Linux kernel for Qualcomm Snapdragon processors

Details

Jason A. Donenfeld discovered that the ACPI implementation in the Linux
kernel did not properly restrict loading SSDT code from an EFI variable. A
privileged attacker could use this to bypass Secure Boot lockdown
restrictions and execute arbitrary code in the kernel. (CVE-2019-20908)

Fan Yang discovered that the mremap implementation in the Linux kernel did
not properly handle DAX Huge Pages. A local attacker with access to DAX
storage could use this to gain administrative privileges. (CVE-2020-10757)

Mauricio Faria de Oliveira discovered that the aufs implementation in the
Linux kernel improperly managed inode reference counts in the
vfsub_dentry_open() method. A local attacker could use this vulnerability
to cause a denial of service. (CVE-2020-11935)

Jason A. Donenfeld discovered that the ACPI implementation...

Jason A. Donenfeld discovered that the ACPI implementation in the Linux
kernel did not properly restrict loading SSDT code from an EFI variable. A
privileged attacker could use this to bypass Secure Boot lockdown
restrictions and execute arbitrary code in the kernel. (CVE-2019-20908)

Fan Yang discovered that the mremap implementation in the Linux kernel did
not properly handle DAX Huge Pages. A local attacker with access to DAX
storage could use this to gain administrative privileges. (CVE-2020-10757)

Mauricio Faria de Oliveira discovered that the aufs implementation in the
Linux kernel improperly managed inode reference counts in the
vfsub_dentry_open() method. A local attacker could use this vulnerability
to cause a denial of service. (CVE-2020-11935)

Jason A. Donenfeld discovered that the ACPI implementation in the Linux
kernel did not properly restrict loading ACPI tables via configfs. A
privileged attacker could use this to bypass Secure Boot lockdown
restrictions and execute arbitrary code in the kernel. (CVE-2020-15780)

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-4.15.0-1050-oracle –  4.15.0-1050.54
linux-image-4.15.0-1066-gke –  4.15.0-1066.69
linux-image-4.15.0-1067-raspi2 –  4.15.0-1067.71
linux-image-4.15.0-1071-kvm –  4.15.0-1071.72
linux-image-4.15.0-1079-aws –  4.15.0-1079.83
linux-image-4.15.0-1080-gcp –  4.15.0-1080.90
linux-image-4.15.0-1092-azure –  4.15.0-1092.102
linux-image-4.15.0-1093-oem –  4.15.0-1093.103
linux-image-4.15.0-112-generic –  4.15.0-112.113
linux-image-4.15.0-112-generic-lpae –  4.15.0-112.113
linux-image-4.15.0-112-lowlatency –  4.15.0-112.113
linux-image-aws-lts-18.04 –  4.15.0.1079.81
linux-image-azure-lts-18.04 –  4.15.0.1092.63
linux-image-gcp-lts-18.04 –  4.15.0.1080.96
linux-image-generic –  4.15.0.112.100
linux-image-generic-lpae –  4.15.0.112.100
linux-image-gke –  4.15.0.1066.68
linux-image-gke-4.15 –  4.15.0.1066.68
linux-image-kvm –  4.15.0.1071.67
linux-image-lowlatency –  4.15.0.112.100
linux-image-oem –  4.15.0.1093.96
linux-image-oracle-lts-18.04 –  4.15.0.1050.59
linux-image-raspi2 –  4.15.0.1067.65
linux-image-virtual –  4.15.0.112.100
16.04 xenial linux-image-4.15.0-1050-oracle –  4.15.0-1050.54~16.04.1
linux-image-4.15.0-1079-aws –  4.15.0-1079.83~16.04.1
linux-image-4.15.0-1080-gcp –  4.15.0-1080.90~16.04.1
linux-image-4.15.0-1092-azure –  4.15.0-1092.102~16.04.1
linux-image-4.15.0-112-generic –  4.15.0-112.113~16.04.1
linux-image-4.15.0-112-generic-lpae –  4.15.0-112.113~16.04.1
linux-image-4.15.0-112-lowlatency –  4.15.0-112.113~16.04.1
linux-image-aws-hwe –  4.15.0.1079.76
linux-image-azure –  4.15.0.1092.87
linux-image-gcp –  4.15.0.1080.82
linux-image-generic-hwe-16.04 –  4.15.0.112.114
linux-image-generic-lpae-hwe-16.04 –  4.15.0.112.114
linux-image-gke –  4.15.0.1080.82
linux-image-lowlatency-hwe-16.04 –  4.15.0.112.114
linux-image-oem –  4.15.0.112.114
linux-image-oracle –  4.15.0.1050.41
linux-image-virtual-hwe-16.04 –  4.15.0.112.114

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References

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