Arch Linux: 201808-4 High: Critical Linux Denial Of Service Risk

Arch Linux Security Advisory ASA-201808-4
========================================
Severity: High
Date    : 2018-08-08
CVE-ID  : CVE-2018-5390
Package : linux
Type    : denial of service
Remote  : Yes
Link    : https://security.archlinux.org/AVG-747

Summary
======
The package linux before version 4.17.11-1 is vulnerable to denial of
service.

Resolution
=========
Upgrade to 4.17.11-1.

# pacman -Syu "linux>=4.17.11-1"

The problem has been fixed upstream in version 4.17.11.

Workaround
=========
None.

Description
==========
A flaw named SegmentSmack was found in the way the Linux kernel handled
specially crafted TCP packets. A remote attacker could use this flaw to
trigger time and calculation expensive calls to
tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() functions by sending
specially modified packets within ongoing TCP sessions which could lead
to a CPU saturation and hence a denial of service on the system.
Maintaining the denial of service condition requires continuous two-way
TCP sessions to a reachable open port, thus the attacks cannot be
performed using spoofed IP addresses.

Impact
=====
A remote attacker is able to saturate the CPU and hence cause a denial
of service on the host system by sending specially modified packets
within ongoing TCP sessions.

References
=========
https://www.kb.cert.org/vuls/id/962459

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/
https://security.archlinux.org/CVE-2018-5390