[ASA-201801-6] linux-lts: access restriction bypass

[Levente Polyak]

Arch Linux Security Advisory ASA-201801-6
=========================================

Severity: High
Date    : 2018-01-08
CVE-ID  : CVE-2017-5754
Package : linux-lts
Type    : access restriction bypass
Remote  : No
Link    : https://security.archlinux.org/AVG-577

Summary
=======

The package linux-lts before version 4.9.75-1 is vulnerable to access
restriction bypass.

Resolution
==========

Upgrade to 4.9.75-1.

# pacman -Syu "linux-lts>=4.9.75-1"

The problem has been fixed upstream in version 4.9.75.

Workaround
==========

None.

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

An industry-wide issue was found in the way many modern microprocessor
designs have implemented speculative execution of instructions (a
commonly used performance optimization).
This variant ("Rogue Data Load") relies on the fact that, on impacted
microprocessors, during speculative execution of instruction permission
faults, exception generation triggered by a faulting access is
suppressed until the retirement of the whole instruction block. In a
combination with the fact that memory accesses may populate the cache
even when the block is being dropped and never committed (executed), an
unprivileged local attacker could use this flaw to read memory from
arbitrary addresses, including privileged (kernel space) and all other
processes running on the system by conducting targeted cache side-
channel attacks.

Impact
======

A local unprivileged attacker is able to read memory from arbitrary
addresses including the kernel and all other processes running on the
system.

References
==========

https://googleprojectzero.blogspot.com/2018/01/reading-privileged-memory-with-side.html
https://meltdownattack.com
https://xenbits.xen.org/xsa/advisory-254.html
http://blog.cyberus-technology.de/posts/2018-01-03-meltdown.html
https://git.kernel.org/linus/5aa90a84589282b87666f92b6c3c917c8080a9bf
https://git.kernel.org/linus/00a5ae218d57741088068799b810416ac249a9ce
https://security.archlinux.org/CVE-2017-5754

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