Ubuntu 21.04: USN-5092-2 Addresses Critical Security Vulnerabilities

ubuntu

September 29, 2021

Several security issues were fixed in the Linux kernel.

Summary

Several security issues were fixed in the Linux kernel.

Software Description:

- linux-azure: Linux kernel for Microsoft Azure Cloud systems

- linux-signed-azure: Signed kernel image azure

- linux-azure-5.11: Linux kernel for Microsoft Azure cloud systems

- linux-hwe-5.11: Linux hardware enablement (HWE) kernel

- linux-oracle-5.11: Linux kernel for Oracle Cloud systems

Details:

Valentina Palmiotti discovered that the io_uring subsystem in the Linux

kernel could be coerced to free adjacent memory. A local attacker could use

this to execute arbitrary code. (CVE-2021-41073)

Ofek Kirzner, Adam Morrison, Benedict Schlueter, and Piotr Krysiuk

discovered that the BPF verifier in the Linux kernel missed possible

mispredicted branches due to type confusion, allowing a side-channel

attack. An attacker could use this to expose sensitive information.

(CVE-2021-33624)

Benedict Schlueter discovered that the BPF subsystem in the Linux kernel

did not properly protect against Speculatively Stor...

Read the Full Advisory

Topics Covered

security advisory denial of service remote attack Ubuntu kernel local attack information disclosure

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 21.04:
  linux-image-5.11.0-1017-azure   5.11.0-1017.18
  linux-image-azure               5.11.0.1017.18

Ubuntu 20.04 LTS:
  linux-image-5.11.0-1017-azure   5.11.0-1017.18~20.04.1
  linux-image-5.11.0-1019-oracle  5.11.0-1019.20~20.04.1
  linux-image-5.11.0-37-generic   5.11.0-37.41~20.04.2
  linux-image-5.11.0-37-generic-64k  5.11.0-37.41~20.04.2
  linux-image-5.11.0-37-generic-lpae  5.11.0-37.41~20.04.2
  linux-image-5.11.0-37-lowlatency  5.11.0-37.41~20.04.2
  linux-image-azure-edge          5.11.0.1017.18~20.04.16
  linux-image-generic-64k-hwe-20.04  5.11.0.37.41~20.04.16
  linux-image-generic-hwe-20.04   5.11.0.37.41~20.04.16
  linux-image-generic-lpae-hwe-20.04  5.11.0.37.41~20.04.16
  linux-image-lowlatency-hwe-20.04  5.11.0.37.41~20.04.16
  linux-image-oracle              5.11.0.1019.20~20.04.12
  linux-image-virtual-hwe-20.04   5.11.0.37.41~20.04.16

After a standard system update you need to reboot your computer to make
all the necessary changes.

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.