Arch Linux 2015-05-15 Advisory: Low Severity Denial Of Service Risk

Arch Linux Security Advisory ASA-201505-15
=========================================
Severity: Low
Date    : 2015-05-26
CVE-ID  : CVE-2015-0847
Package : nbd
Type    : denial of service
Remote  : Yes
Link    : https://wiki.archlinux.org/title/CVE

Summary
======
The package nbd before version 3.11-1 is vulnerable to denial of service.

Resolution
=========
Upgrade to 3.11-1.

# pacman -Syu "nbd>=3.11-1"

The problem has been fixed upstream in version 3.11.

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

Description
==========
Signal handlers themselves were entered only once, but they called
posixly unsafe, non-reentrant functions, such as syslog(). If a signal
was caught in the middle of the execution of such function, consequences
were undefined. In practice, nbd-server was observed to deadlock during
the execution of sigchld_handler().

Impact
=====
A remote attacker is able to send requests to the nbd server that may
lead to a deadlock resulting in denial of service.

References
=========

https://access.redhat.com/security/cve/CVE-2015-0847
https://github.com/NetworkBlockDevice/nbd/commit/412def