[FROG] Advisory - FRR BGP peer flaps @ 2019-01-07

[Quentin Young]

Hello operators,

This morning some users running FRR BGP noticed that their sessions were
flapping. Investigation revealed that this was caused by an experiment being
run by SwiNOG [0] which was triggering an undesired code path in FRR.
Specifically, FRR uses attribute type 0xFF as the attribute code for VNC [1].
This code was intended to be turned off by default, but our current published
builds [2] have it turned on. Consequently, bgpd attempts to parse the received
attribute as a VNC attribute and fails, triggering a session reset.

We have a patch in testing now and expect to have new build artifacts published
shortly. Additionally, we have contacted the experiment operators and requested
a pause in the experiment while we handle this issue.

Thank you to the operators that notified us this morning!

- FRR maintainer team

[0] http://lists.swinog.ch/public/swinog/2018-December/007110.html
[1] http://docs.frrouting.org/en/latest/vnc.html
[2] https://github.com/FRRouting/frr/releases