1. Ubuntu Security Notices
  2. USN-4950-1

USN-4950-1: Linux kernel vulnerabilities

Publication date

11 May 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-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

Details

Ryota Shiga discovered that the eBPF implementation in the Linux kernel did
not properly verify that a BPF program only reserved as much memory for a
ring buffer as was allocated. A local attacker could use this to cause a
denial of service (system crash) or execute arbitrary code. (CVE-2021-3489)

Manfred Paul discovered that the eBPF implementation in the Linux kernel
did not properly track bounds on bitwise operations. A local attacker could
use this to cause a denial of service (system crash) or execute arbitrary
code. (CVE-2021-3490)

Billy Jheng Bing-Jhong discovered that the io_uring implementation of the
Linux kernel did not properly enforce the MAX_RW_COUNT limit in some
situations. A local attacker could use this to cause a denial of service
(system crash) or execute arbitrary code. (

Ryota Shiga discovered that the eBPF implementation in the Linux kernel did
not properly verify that a BPF program only reserved as much memory for a
ring buffer as was allocated. A local attacker could use this to cause a
denial of service (system crash) or execute arbitrary code. (CVE-2021-3489)

Manfred Paul discovered that the eBPF implementation in the Linux kernel
did not properly track bounds on bitwise operations. A local attacker could
use this to cause a denial of service (system crash) or execute arbitrary
code. (CVE-2021-3490)

Billy Jheng Bing-Jhong discovered that the io_uring implementation of the
Linux kernel did not properly enforce the MAX_RW_COUNT limit in some
situations. A local attacker could use this to cause a denial of service
(system crash) or execute arbitrary code. (CVE-2021-3491)

Norbert Slusarek discovered that the CAN ISOTP protocol implementation
in the Linux kernel contained a race condition. A local attacker could
use this to cause a denial of service (system crash) or possibly
execute arbitrary code. Please note that to address this issue,
SF_BROADCAST support was removed temporarily from the CAN ISOTP
implementation in Ubuntu 21.04 kernels. (LP: #1927409)

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
21.04 hirsute linux-image-5.11.0-1005-azure –  5.11.0-1005.5
linux-image-5.11.0-1006-oracle –  5.11.0-1006.6
linux-image-5.11.0-1007-aws –  5.11.0-1007.7
linux-image-5.11.0-1007-gcp –  5.11.0-1007.7
linux-image-5.11.0-1007-kvm –  5.11.0-1007.7
linux-image-5.11.0-1008-raspi –  5.11.0-1008.8
linux-image-5.11.0-1008-raspi-nolpae –  5.11.0-1008.8
linux-image-5.11.0-17-generic –  5.11.0-17.18
linux-image-5.11.0-17-generic-64k –  5.11.0-17.18
linux-image-5.11.0-17-generic-lpae –  5.11.0-17.18
linux-image-5.11.0-17-lowlatency –  5.11.0-17.18
linux-image-aws –  5.11.0.1007.7
linux-image-azure –  5.11.0.1005.5
linux-image-gcp –  5.11.0.1007.7
linux-image-generic –  5.11.0.17.18
linux-image-generic-64k –  5.11.0.17.18
linux-image-generic-lpae –  5.11.0.17.18
linux-image-gke –  5.11.0.1007.7
linux-image-kvm –  5.11.0.1007.7
linux-image-lowlatency –  5.11.0.17.18
linux-image-oracle –  5.11.0.1006.6
linux-image-raspi –  5.11.0.1008.6
linux-image-raspi-nolpae –  5.11.0.1008.6
linux-image-virtual –  5.11.0.17.18

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References

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