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Vulnerability of Linux kernel: use after free via btrfs_queue_work

Synthesis of the vulnerability 

An attacker can force the usage of a freed memory area via btrfs_queue_work() of the Linux kernel, in order to trigger a denial of service, and possibly to run code.
Vulnerable systems: Linux, Ubuntu.
Severity of this threat: 2/4.
Creation date: 02/12/2019.
Références of this weakness: CERTFR-2020-AVI-307, CERTFR-2020-AVI-312, CERTFR-2020-AVI-326, CERTFR-2020-AVI-421, CVE-2019-19377, USN-4367-1, USN-4367-2, USN-4369-1, USN-4369-2, USN-4414-1, VIGILANCE-VUL-31034.

Description of the vulnerability 

An attacker can force the usage of a freed memory area via btrfs_queue_work() of the Linux kernel, in order to trigger a denial of service, and possibly to run code.
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This computer weakness impacts software or systems such as Linux, Ubuntu.

Our Vigil@nce team determined that the severity of this vulnerability note is medium.

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

A proof of concept or an attack tool is available, so your teams have to process this alert. An attacker with a technician ability can exploit this cybersecurity threat.

Solutions for this threat 

Linux kernel: version 5.6.5.
The version 5.6.5 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v5.x/

Linux kernel: version 5.5.18.
The version 5.5.18 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v5.x/

Linux kernel: version 5.4.33.
The version 5.4.33 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v5.x/

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

Ubuntu 20.04 LTS: new linux-image-5.4.0 packages.
New packages are available, as indicated in information sources.

Ubuntu: new linux-image-4.15.0 packages.
New packages are available:
  Ubuntu 16.04 LTS: linux-image-generic-hwe-16.04 4.15.0.107.112
  Ubuntu 18.04 LTS: linux-image-generic 4.15.0.109.97

Ubuntu: new linux-image-5.3.0 packages.
New packages are available:
  Ubuntu 18.04 LTS: linux-image-generic-hwe-18.04 5.3.0.53.109
  Ubuntu 19.10: linux-image-generic 5.3.0.53.45
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Computer vulnerabilities tracking service 

Vigil@nce provides network vulnerability alerts. The Vigil@nce security watch publishes vulnerability bulletins about threats impacting the information system.