Arch Linux: ASA-201701-32 Medium Risk of Privilege Escalation in Kernel

Arch Linux Security Advisory ASA-201701-32
=========================================
Severity: Medium
Date    : 2017-01-27
CVE-ID  : CVE-2017-2583
Package : linux
Type    : privilege escalation
Remote  : No
Link    : https://security.archlinux.org/AVG-149

Summary
======
The package linux before version 4.9.5-1 is vulnerable to privilege
escalation.

Resolution
=========
Upgrade to 4.9.5-1.

# pacman -Syu "linux>=4.9.5-1"

The problem has been fixed upstream in version 4.9.5.

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

Description
==========
The Linux kernel > 3.6-rc1, when built with Kernel-based Virtual
Machine (CONFIG_KVM) support, is vulnerable to an incorrect segment
selector (SS) value error. It could occur loading values into SS
register in long mode.
A user/process inside a guest host could use this flaw to crash the
guest, resulting in denial of service, or potentially escalate their
privileges inside the guest system on an AMD processor.

Impact
=====
A local attacker in a guest host is able to crash the system or
escalate privileges inside the guest on an AMD processor.

References
=========
https://seclists.org/oss-sec/2017/q1/137
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/
https://security.archlinux.org/CVE-2017-2583