1. Ubuntu Security Notices
  2. USN-5018-1

USN-5018-1: Linux kernel vulnerabilities

Publication date

20 July 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-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-raspi2 - Linux kernel for Raspberry Pi (V8) systems
  • linux-snapdragon - Linux kernel for Qualcomm Snapdragon processors

Details

It was discovered that the virtual file system implementation in the Linux
kernel contained an unsigned to signed integer conversion error. A local
attacker could use this to cause a denial of service (system crash) or
execute arbitrary code. (CVE-2021-33909)

Piotr Krysiuk discovered that the eBPF implementation in the Linux kernel
did not properly enforce limits for pointer operations. A local attacker
could use this to cause a denial of service (system crash) or possibly
execute arbitrary code. (CVE-2021-33200)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation did
not properly clear received fragments from memory in some situations. A
physically proximate attacker could possibly use this issue to inject
packets or expose sensitive information. (CVE-2020-24586)

Mathy Vanhoef discovered...

It was discovered that the virtual file system implementation in the Linux
kernel contained an unsigned to signed integer conversion error. A local
attacker could use this to cause a denial of service (system crash) or
execute arbitrary code. (CVE-2021-33909)

Piotr Krysiuk discovered that the eBPF implementation in the Linux kernel
did not properly enforce limits for pointer operations. A local attacker
could use this to cause a denial of service (system crash) or possibly
execute arbitrary code. (CVE-2021-33200)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation did
not properly clear received fragments from memory in some situations. A
physically proximate attacker could possibly use this issue to inject
packets or expose sensitive information. (CVE-2020-24586)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation
incorrectly handled encrypted fragments. A physically proximate attacker
could possibly use this issue to decrypt fragments. (CVE-2020-24587)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation
incorrectly handled EAPOL frames from unauthenticated senders. A physically
proximate attacker could inject malicious packets to cause a denial of
service (system crash). (CVE-2020-26139)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation could
reassemble mixed encrypted and plaintext fragments. A physically proximate
attacker could possibly use this issue to inject packets or exfiltrate
selected fragments. (CVE-2020-26147)

It was discovered that the bluetooth subsystem in the Linux kernel did not
properly perform access control. An authenticated attacker could possibly
use this to expose sensitive information. (CVE-2020-26558, CVE-2021-0129)

Or Cohen and Nadav Markus discovered a use-after-free vulnerability in the
nfc implementation in the Linux kernel. A privileged local attacker could
use this issue to cause a denial of service (system crash) or possibly
execute arbitrary code. (CVE-2021-23134)

Piotr Krysiuk discovered that the eBPF implementation in the Linux kernel
did not properly prevent speculative loads in certain situations. A local
attacker could use this to expose sensitive information (kernel memory).
(CVE-2021-31829)

It was discovered that a race condition in the kernel Bluetooth subsystem
could lead to use-after-free of slab objects. An attacker could use this
issue to possibly execute arbitrary code. (CVE-2021-32399)

It was discovered that a use-after-free existed in the Bluetooth HCI driver
of the Linux kernel. A local attacker could use this to cause a denial of
service (system crash) or possibly execute arbitrary code. (CVE-2021-33034)

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-4.15.0-1078-oracle –  4.15.0-1078.86
linux-image-4.15.0-1092-raspi2 –  4.15.0-1092.98
linux-image-4.15.0-1097-kvm –  4.15.0-1097.99
linux-image-4.15.0-1106-gcp –  4.15.0-1106.120
linux-image-4.15.0-1109-aws –  4.15.0-1109.116
linux-image-4.15.0-1109-snapdragon –  4.15.0-1109.118
linux-image-4.15.0-1121-azure –  4.15.0-1121.134
linux-image-4.15.0-151-generic –  4.15.0-151.157
linux-image-4.15.0-151-generic-lpae –  4.15.0-151.157
linux-image-4.15.0-151-lowlatency –  4.15.0-151.157
linux-image-aws-lts-18.04 –  4.15.0.1109.112
linux-image-azure-lts-18.04 –  4.15.0.1121.94
linux-image-gcp-lts-18.04 –  4.15.0.1106.125
linux-image-generic –  4.15.0.151.139
linux-image-generic-lpae –  4.15.0.151.139
linux-image-kvm –  4.15.0.1097.93
linux-image-lowlatency –  4.15.0.151.139
linux-image-oracle-lts-18.04 –  4.15.0.1078.88
linux-image-raspi2 –  4.15.0.1092.90
linux-image-snapdragon –  4.15.0.1109.112
linux-image-virtual –  4.15.0.151.139
16.04 xenial linux-image-4.15.0-1078-oracle –  4.15.0-1078.86~16.04.1  
linux-image-4.15.0-1106-gcp –  4.15.0-1106.120~16.04.1  
linux-image-4.15.0-1109-aws –  4.15.0-1109.116~16.04.1  
linux-image-4.15.0-1121-azure –  4.15.0-1121.134~16.04.1  
linux-image-4.15.0-151-generic –  4.15.0-151.157~16.04.1  
linux-image-4.15.0-151-lowlatency –  4.15.0-151.157~16.04.1  
linux-image-aws-hwe –  4.15.0.1109.100  
linux-image-azure –  4.15.0.1121.112  
linux-image-gcp –  4.15.0.1106.107  
linux-image-generic-hwe-16.04 –  4.15.0.151.146  
linux-image-gke –  4.15.0.1106.107  
linux-image-lowlatency-hwe-16.04 –  4.15.0.151.146  
linux-image-oem –  4.15.0.151.146  
linux-image-oracle –  4.15.0.1078.66  
linux-image-virtual-hwe-16.04 –  4.15.0.151.146  
14.04 trusty linux-image-4.15.0-1121-azure –  4.15.0-1121.134~14.04.1  
linux-image-azure –  4.15.0.1121.94  

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References

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