Ubuntu 21.04: USN-5086-1 Critical: Kernel Crash Risk for s390x

ubuntu

September 22, 2021

IBM s390x systems could be made to crash or run programs as an administrator.

Summary

IBM s390x systems could be made to crash or run programs as an

administrator.

Software Description:

- linux: Linux kernel

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

- linux-hwe-5.4: Linux hardware enablement (HWE) kernel

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

Details:

Johan Almbladh discovered that the eBPF JIT implementation for IBM

s390x systems in the Linux kernel miscompiled operations in some

situations, allowing circumvention of the BPF verifier. A local

attacker could use this to cause a denial of service (system crash)

or possibly execute arbitrary code.

Topics Covered

security advisory denial of service critical issue kernel update ubuntu administrative access s390x

Update Instructions

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

Ubuntu 21.04:
  linux-image-5.11.0-36-generic   5.11.0-36.40
  linux-image-5.11.0-36-generic-64k  5.11.0-36.40
  linux-image-5.11.0-36-generic-lpae  5.11.0-36.40
  linux-image-5.11.0-36-lowlatency  5.11.0-36.40
  linux-image-generic             5.11.0.36.38
  linux-image-generic-64k         5.11.0.36.38
  linux-image-generic-lpae        5.11.0.36.38
  linux-image-lowlatency          5.11.0.36.38
  linux-image-oem-20.04           5.11.0.36.38
  linux-image-virtual             5.11.0.36.38

Ubuntu 20.04 LTS:
  linux-image-5.11.0-36-generic   5.11.0-36.40~20.04.1
  linux-image-5.11.0-36-generic-64k  5.11.0-36.40~20.04.1
  linux-image-5.11.0-36-generic-lpae  5.11.0-36.40~20.04.1
  linux-image-5.11.0-36-lowlatency  5.11.0-36.40~20.04.1
  linux-image-5.4.0-86-generic    5.4.0-86.97
  linux-image-5.4.0-86-generic-lpae  5.4.0-86.97
  linux-image-5.4.0-86-lowlatency  5.4.0-86.97
  linux-image-generic             5.4.0.86.90
  linux-image-generic-64k-hwe-20.04  5.11.0.36.40~20.04.15
  linux-image-generic-hwe-20.04   5.11.0.36.40~20.04.15
  linux-image-generic-lpae        5.4.0.86.90
  linux-image-generic-lpae-hwe-20.04  5.11.0.36.40~20.04.15
  linux-image-lowlatency          5.4.0.86.90
  linux-image-lowlatency-hwe-20.04  5.11.0.36.40~20.04.15
  linux-image-oem                 5.4.0.86.90
  linux-image-oem-osp1            5.4.0.86.90
  linux-image-virtual             5.4.0.86.90
  linux-image-virtual-hwe-20.04   5.11.0.36.40~20.04.15

Ubuntu 18.04 LTS:
  linux-image-4.15.0-158-generic  4.15.0-158.166
  linux-image-4.15.0-158-generic-lpae  4.15.0-158.166
  linux-image-4.15.0-158-lowlatency  4.15.0-158.166
  linux-image-5.4.0-86-generic    5.4.0-86.97~18.04.1
  linux-image-5.4.0-86-generic-lpae  5.4.0-86.97~18.04.1
  linux-image-5.4.0-86-lowlatency  5.4.0-86.97~18.04.1
  linux-image-generic             4.15.0.158.147
  linux-image-generic-hwe-18.04   5.4.0.86.97~18.04.77
  linux-image-generic-lpae        4.15.0.158.147
  linux-image-generic-lpae-hwe-18.04  5.4.0.86.97~18.04.77
  linux-image-lowlatency          4.15.0.158.147
  linux-image-lowlatency-hwe-18.04  5.4.0.86.97~18.04.77
  linux-image-oem                 5.4.0.86.97~18.04.77
  linux-image-oem-osp1            5.4.0.86.97~18.04.77
  linux-image-snapdragon-hwe-18.04  5.4.0.86.97~18.04.77
  linux-image-virtual             4.15.0.158.147
  linux-image-virtual-hwe-18.04   5.4.0.86.97~18.04.77

Ubuntu 16.04 ESM:
  linux-image-4.15.0-158-generic  4.15.0-158.166~16.04.1
  linux-image-4.15.0-158-lowlatency  4.15.0-158.166~16.04.1
  linux-image-4.4.0-216-generic   4.4.0-216.249
  linux-image-4.4.0-216-lowlatency  4.4.0-216.249
  linux-image-generic             4.4.0.216.223
  linux-image-generic-hwe-16.04   4.15.0.158.151
  linux-image-lowlatency          4.4.0.216.223
  linux-image-lowlatency-hwe-16.04  4.15.0.158.151
  linux-image-oem                 4.15.0.158.151
  linux-image-virtual             4.4.0.216.223
  linux-image-virtual-hwe-16.04   4.15.0.158.151

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.