Subject: [ASA-201610-16] linux-grsec: privilege escalation

Arch Linux Security Advisory ASA-201610-16
==========================================

Severity: High
Date    : 2016-10-24
CVE-ID  : CVE-2016-5195
Package : linux-grsec
Type    : privilege escalation
Remote  : No
Link    : https://security.archlinux.org/AVG-49

Summary
=======

The package linux-grsec before version 1:4.7.10.r201610222037-1 is
vulnerable to privilege escalation.

Resolution
==========

Upgrade to 1:4.7.10.r201610222037-1.

# pacman -Syu "linux-grsec>=1:4.7.10.r201610222037-1"

The problem has been fixed upstream in version 4.7.10.r201610222037.

Workaround
==========

None.

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

A race condition was found in the way the Linux kernel's memory
subsystem handled the copy-on-write (COW) breakage of private read-only
memory mappings. An unprivileged local user could use this flaw to gain
write access to otherwise read-only memory mappings and thus increase
their privileges on the system.

Impact
======

An unprivileged local attacker is able to elevate their privileges on
the system and gain root access.

References
==========

https://github.com/dirtycow/dirtycow.github.io/wiki/VulnerabilityDetails
https://bugzilla.redhat.com/show_bug.cgi?id=1384344
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=19be0eaffa3ac7d8eb6784ad9bdbc7d67ed8e619
https://security.archlinux.org/CVE-2016-5195