Subject: [ASA-201612-5] linux-grsec: privilege escalation

Arch Linux Security Advisory ASA-201612-5
=========================================

Severity: High
Date    : 2016-12-06
CVE-ID  : CVE-2016-8655
Package : linux-grsec
Type    : privilege escalation
Remote  : No
Link    : https://security.archlinux.org/AVG-97

Summary
=======

The package linux-grsec before version 1:4.8.12.r201612031658-2 is
vulnerable to privilege escalation.

Resolution
==========

Upgrade to 1:4.8.12.r201612031658-2.

# pacman -Syu "linux-grsec>=1:4.8.12.r201612031658-2"

The problem has been fixed upstream but no release is available yet.

Workaround
==========

None.

Description
===========

A race condition issue leading to a use-after-free flaw was found in
the way the raw packet sockets implementation in the Linux kernel
networking subsystem handled synchronization while creating the
TPACKET_V3 ring buffer. A local user able to open a raw packet socket
(requires the CAP_NET_RAW capability) could use this flaw to elevate
their privileges on the system.

Impact
======

A local unprivileged attacker is able to crash the system or run
arbitrary code with administrative privileges.

References
==========

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=84ac7260236a49c79eede91617700174c2c19b0c
http://seclists.org/oss-sec/2016/q4/607
https://security.archlinux.org/CVE-2016-8655