On Arch X64 using 218-1 (first packaging of 218) I have run into the
following wierd problem.

When trying to connect to a ssh server running dualstack (both ipv4 and
ipv6) by ipv6, ssh segfaults when I have loaded the full ipv4 bgp
routing table (~500k+ routes). IPv4 connections works for some reason,
and Ipv6 recovers if I kill the routing daemon (bird).

The stack trace of the core-file starts with

Stack trace of thread 515:
#0  0x00007f48334a3dd5 _int_free (libc.so.6)
#1  0x00007f4834a1e62a sd_rtnl_message_unref (libnss_myhostname.so.2)
#2  0x00007f4834a1e657 sd_rtnl_message_unref (libnss_myhostname.so.2)

And continues with that line (#1 and #2) until frame 63.

I have looked in src/libsystemd/sd-rtnl/rtnl-message.c and have two
observations (my C is very rusty so feel free to correct me).

Line 589, shouldn't the line
    if (m && REFCNT_DEC(m->n_ref) <=3D 0) {

be

    if (m && REFCNT_DEC(m->n_ref) >=3D 0) {

(I.e. greater-than-equal instead of less-than-equal)

Also, perhaps a test of whether m->next is equal to m on line 597....