CVE-2016-6301: busybox: NTP server denial of service flaw

[Martin Prpic <mprpic () redhat com>]

Miroslav Lichvar of Red Hat reported a flaw in busybox's NTP
implementation:

The busybox NTP implementation doesn't check the NTP mode of packets
received on the server port and responds to any packet with the right
size. This includes responses from another NTP server. An attacker can
send a packet with a spoofed source address in order to create an
infinite loop of responses between two busybox NTP servers. Adding more
packets to the loop increases the traffic between the servers until one
of them has a fully loaded CPU and/or network.

Upstream patch:

https://git.busybox.net/busybox/commit/?id=150dc7a2b483b8338a3e185c478b4b23ee884e71

RH bug:

https://bugzilla.redhat.com/show_bug.cgi?id=1363710

-- 
Martin Prpič / Red Hat Product Security