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Vulnerability of Linux kernel: infinite loop via update_blocked_averages

Synthesis of the vulnerability 

An attacker can trigger an infinite loop via update_blocked_averages() of the Linux kernel, in order to trigger a denial of service.
Impacted products: Linux, RHEL, SIMATIC, Ubuntu.
Severity of this bulletin: 1/4.
Creation date: 25/02/2019.
Références of this threat: CERTFR-2019-AVI-361, CERTFR-2019-AVI-419, CERTFR-2019-AVI-441, CERTFR-2019-AVI-602, CVE-2018-20784, RHSA-2019:1959-01, RHSA-2019:1971-01, SSB-439005, USN-4115-1, USN-4115-2, USN-4118-1, USN-4211-1, USN-4211-2, VIGILANCE-VUL-28593.

Description of the vulnerability 

An attacker can trigger an infinite loop via update_blocked_averages() of the Linux kernel, in order to trigger a denial of service.
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This cybersecurity bulletin impacts software or systems such as Linux, RHEL, SIMATIC, Ubuntu.

Our Vigil@nce team determined that the severity of this cybersecurity weakness is low.

The trust level is of type confirmed by the editor, with an origin of user shell.

An attacker with a expert ability can exploit this computer vulnerability bulletin.

Solutions for this threat 

Linux kernel: version 4.20.2.
The version 4.20.2 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v4.x/

Linux kernel: version 4.19.15.
The version 4.19.15 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v4.x/

Linux kernel: patch for update_blocked_averages.
A patch is indicated in information sources.

RHEL 8.0: new kernel packages.
New packages are available:
  RHEL 8: kernel 4.18.0-80.7.1.el8_0

RHEL 8.0: new kernel-rt packages.
New packages are available:
  RHEL 8: kernel-rt 4.18.0-80.7.1.rt9.153.el8_0

SIMATIC S7-1500 CPU 1518: workaround for GNU/Linux Vulnerabilities.
A workaround is indicated in the information source.

Ubuntu 16/18: new linux-image-aws packages.
New packages are available:
  Ubuntu 16.04 LTS: linux-image-aws 4.15.0.1047.47
  Ubuntu 18.04 LTS: linux-image-aws 4.15.0.1047.46

Ubuntu: new linux-image-4.15.0 packages.
New packages are available:
  Ubuntu 16.04 LTS: linux-image-generic-hwe-16.04 4.15.0.62.82
  Ubuntu 18.04 LTS: linux-image-generic 4.15.0.62.64

Ubuntu: new linux-image-4.4.0 packages.
New packages are available:
  Ubuntu 14.04 ESM: linux-image-generic-lts-xenial 4.4.0.170.149
  Ubuntu 16.04 LTS: linux-image-generic 4.4.0.170.178

Wind River Linux: solution (21/05/2019).
The solution is indicated in information sources.
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