[arch-security] [ASA-201710-28] musl: arbitrary code execution

[Remi Gacogne]

Arch Linux Security Advisory ASA-201710-28
==========================================

Severity: Critical
Date    : 2017-10-21
CVE-ID  : CVE-2017-15650
Package : musl
Type    : arbitrary code execution
Remote  : Yes
Link    : https://security.archlinux.org/AVG-457

Summary
=======

The package musl before version 1.1.17-1 is vulnerable to arbitrary
code execution.

Resolution
==========

Upgrade to 1.1.17-1.

# pacman -Syu "musl>=1.1.17-1"

The problem has been fixed upstream in version 1.1.17.

Workaround
==========

Using a local, trusted DNS resolver mitigates the issue.

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

A stack-based buffer overflow has been found in the DNS response
parsing code of musl libc <= 1.1.16. When an application makes a
request via getaddrinfo for both IPv4 and IPv6 results (AF_UNSPEC), an
attacker who controls or can spoof the nameservers configured in
resolv.conf can reply to both the A and AAAA queries with A results.
Since A records are smaller than AAAA records, it's possible to fit
more addresses than the precomputed bound, and a buffer overflow
occurs.

Impact
======

A remote attacker who controls or can spoof the nameservers configured
in resolv.conf can execute arbitrary code on the affected host.

References
==========

http://seclists.org/oss-sec/2017/q4/107
https://git.musl-libc.org/cgit/musl/commit/?id=45ca5d3fcb6f874bf5ba55d0e9651cef68515395
https://security.archlinux.org/CVE-2017-15650

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