USN-4910-1: Linux kernel vulnerabilities

Publication date

13 April 2021

Overview

Several security issues were fixed in the Linux kernel.


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-hwe-5.8 - Linux hardware enablement (HWE) kernel
  • 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 sockopt BPF hooks in the Linux kernel could
allow a user space program to probe for valid kernel addresses. A local
attacker could use this to ease exploitation of another kernel
vulnerability. (CVE-2021-20239)

It was discovered that the BPF verifier in the Linux kernel did not
properly handle signed add32 and sub integer overflows. A local attacker
could use this to cause a denial of service (system crash) or possibly
execute arbitrary code. (CVE-2021-20268)

It was discovered that the priority inheritance futex implementation in the
Linux kernel contained a race condition, leading to a use-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2021-3347)

It was discovered that the network...

Ryota Shiga discovered that the sockopt BPF hooks in the Linux kernel could
allow a user space program to probe for valid kernel addresses. A local
attacker could use this to ease exploitation of another kernel
vulnerability. (CVE-2021-20239)

It was discovered that the BPF verifier in the Linux kernel did not
properly handle signed add32 and sub integer overflows. A local attacker
could use this to cause a denial of service (system crash) or possibly
execute arbitrary code. (CVE-2021-20268)

It was discovered that the priority inheritance futex implementation in the
Linux kernel contained a race condition, leading to a use-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2021-3347)

It was discovered that the network block device (nbd) driver in the Linux
kernel contained a use-after-free vulnerability during device setup. A
local attacker with access to the nbd device could use this to cause a
denial of service (system crash) or possibly execute arbitrary code.
(CVE-2021-3348)

吴异 discovered that the NFS implementation in the Linux kernel did not
properly prevent access outside of an NFS export that is a subdirectory of
a file system. An attacker could possibly use this to bypass NFS access
restrictions. (CVE-2021-3178)


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
20.10 groovy linux-image-5.8.0-1020-raspi –  5.8.0-1020.23
linux-image-5.8.0-1020-raspi-nolpae –  5.8.0-1020.23
linux-image-5.8.0-1023-kvm –  5.8.0-1023.25
linux-image-5.8.0-1025-oracle –  5.8.0-1025.26
linux-image-5.8.0-1027-azure –  5.8.0-1027.29
linux-image-5.8.0-1027-gcp –  5.8.0-1027.28
linux-image-5.8.0-1028-aws –  5.8.0-1028.30
linux-image-5.8.0-49-generic –  5.8.0-49.55
linux-image-5.8.0-49-generic-64k –  5.8.0-49.55
linux-image-5.8.0-49-generic-lpae –  5.8.0-49.55
linux-image-5.8.0-49-lowlatency –  5.8.0-49.55
linux-image-aws –  5.8.0.1028.30
linux-image-azure –  5.8.0.1027.27
linux-image-gcp –  5.8.0.1027.27
linux-image-generic –  5.8.0.49.54
linux-image-generic-64k –  5.8.0.49.54
linux-image-generic-lpae –  5.8.0.49.54
linux-image-gke –  5.8.0.1027.27
linux-image-kvm –  5.8.0.1023.25
linux-image-lowlatency –  5.8.0.49.54
linux-image-oem-20.04 –  5.8.0.49.54
linux-image-oracle –  5.8.0.1025.24
linux-image-raspi –  5.8.0.1020.23
linux-image-raspi-nolpae –  5.8.0.1020.23
linux-image-virtual –  5.8.0.49.54
20.04 focal linux-image-5.8.0-49-generic –  5.8.0-49.55~20.04.1
linux-image-5.8.0-49-generic-64k –  5.8.0-49.55~20.04.1
linux-image-5.8.0-49-generic-lpae –  5.8.0-49.55~20.04.1
linux-image-5.8.0-49-lowlatency –  5.8.0-49.55~20.04.1
linux-image-generic-64k-hwe-20.04 –  5.8.0.49.55~20.04.33
linux-image-generic-hwe-20.04 –  5.8.0.49.55~20.04.33
linux-image-generic-lpae-hwe-20.04 –  5.8.0.49.55~20.04.33
linux-image-lowlatency-hwe-20.04 –  5.8.0.49.55~20.04.33
linux-image-virtual-hwe-20.04 –  5.8.0.49.55~20.04.33

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