Ubuntu 21.04: 5014-1 Critical: Linux Kernel Denial of Service Attack

ubuntu

July 20, 2021

The system could be made to run programs as an administrator.

Summary

The system could be made to run programs as an administrator.

Software Description:

- 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

- linux-gke-5.3: Linux kernel for Google Container Engine (GKE) systems

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

- linux-raspi2-5.3: Linux kernel for Raspberry Pi (V8) systems

- linux-lts-xenial: Linux hardware enablement kernel from Xenial for Trusty

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.

Topics Covered

security advisory denial of service critical issue ubuntu linux kernel local attacker

Update Instructions

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

Ubuntu 21.04:
  linux-image-5.11.0-1012-azure   5.11.0-1012.13
  linux-image-5.11.0-1012-kvm     5.11.0-1012.13
  linux-image-5.11.0-1013-oracle  5.11.0-1013.14
  linux-image-5.11.0-1014-aws     5.11.0-1014.15
  linux-image-5.11.0-1014-gcp     5.11.0-1014.16
  linux-image-5.11.0-1015-raspi   5.11.0-1015.16
  linux-image-5.11.0-1015-raspi-nolpae  5.11.0-1015.16
  linux-image-5.11.0-25-generic   5.11.0-25.27
  linux-image-5.11.0-25-generic-64k  5.11.0-25.27
  linux-image-5.11.0-25-generic-lpae  5.11.0-25.27
  linux-image-5.11.0-25-lowlatency  5.11.0-25.27
  linux-image-aws                 5.11.0.1014.15
  linux-image-azure               5.11.0.1012.13
  linux-image-gcp                 5.11.0.1014.14
  linux-image-generic             5.11.0.25.27
  linux-image-generic-64k         5.11.0.25.27
  linux-image-generic-lpae        5.11.0.25.27
  linux-image-gke                 5.11.0.1014.14
  linux-image-kvm                 5.11.0.1012.13
  linux-image-lowlatency          5.11.0.25.27
  linux-image-oem-20.04           5.11.0.25.27
  linux-image-oracle              5.11.0.1013.14
  linux-image-raspi               5.11.0.1015.13
  linux-image-raspi-nolpae        5.11.0.1015.13
  linux-image-virtual             5.11.0.25.27

Ubuntu 18.04 LTS:
  linux-image-5.3.0-1042-raspi2   5.3.0-1042.44
  linux-image-5.3.0-1045-gke      5.3.0-1045.48
  linux-image-5.3.0-76-generic    5.3.0-76.72
  linux-image-5.3.0-76-lowlatency  5.3.0-76.72
  linux-image-gke-5.3             5.3.0.1045.28
  linux-image-gkeop-5.3           5.3.0.76.133
  linux-image-raspi2-hwe-18.04    5.3.0.1042.31

Ubuntu 16.04 ESM:
  linux-image-4.4.0-1095-kvm      4.4.0-1095.104
  linux-image-4.4.0-1130-aws      4.4.0-1130.144
  linux-image-4.4.0-212-generic   4.4.0-212.244
  linux-image-4.4.0-212-lowlatency  4.4.0-212.244
  linux-image-aws                 4.4.0.1130.135
  linux-image-generic             4.4.0.212.219
  linux-image-kvm                 4.4.0.1095.93
  linux-image-lowlatency          4.4.0.212.219
  linux-image-virtual             4.4.0.212.219

Ubuntu 14.04 ESM:
  linux-image-3.13.0-186-generic  3.13.0-186.237
  linux-image-3.13.0-186-generic-lpae  3.13.0-186.237
  linux-image-3.13.0-186-lowlatency  3.13.0-186.237
  linux-image-3.13.0-186-powerpc-e500  3.13.0-186.237
  linux-image-3.13.0-186-powerpc-e500mc  3.13.0-186.237
  linux-image-3.13.0-186-powerpc-smp  3.13.0-186.237
  linux-image-3.13.0-186-powerpc64-emb  3.13.0-186.237
  linux-image-3.13.0-186-powerpc64-smp  3.13.0-186.237
  linux-image-4.4.0-1094-aws      4.4.0-1094.99
  linux-image-4.4.0-212-generic   4.4.0-212.244~14.04.1
  linux-image-4.4.0-212-lowlatency  4.4.0-212.244~14.04.1
  linux-image-aws                 4.4.0.1094.92
  linux-image-generic             3.13.0.186.195
  linux-image-generic-lpae        3.13.0.186.195
  linux-image-generic-lts-xenial  4.4.0.212.185
  linux-image-generic-pae         3.13.0.186.195
  linux-image-highbank            3.13.0.186.195
  linux-image-lowlatency          3.13.0.186.195
  linux-image-lowlatency-lts-xenial  4.4.0.212.185
  linux-image-lowlatency-pae      3.13.0.186.195
  linux-image-omap                3.13.0.186.195
  linux-image-powerpc-e500        3.13.0.186.195
  linux-image-powerpc-e500mc      3.13.0.186.195
  linux-image-powerpc-smp         3.13.0.186.195
  linux-image-powerpc64-emb       3.13.0.186.195
  linux-image-powerpc64-smp       3.13.0.186.195
  linux-image-server              3.13.0.186.195
  linux-image-virtual             3.13.0.186.195
  linux-image-virtual-lts-xenial  4.4.0.212.185

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.