FreeBSD 11.1-RELEASE: Kernel panic in ipv6_output() via tcp6_usr_connect()

[Viktor Dukhovni]

On Wed, Nov 01, 2017 at 02:17:33PM +0300, Andrey V. Elsukov wrote:

> > # NAT the rest
> > ipfw nat 1 config if "$oif" unreg_only reset same_ports
> > ipfw add nat 1 ip from any to any via "$oif"
> 
> Just an theory, can you try change this rule to be like this:
> 
>  ipfw add nat 1 ip4 from any to any via "$oif"
> 
> From first glance I don't see any restrictions in libalias/nat44 to not
> try to translate IPv6 packet assuming it as IPv4.

I've changed the rule from "ip" to "ip4", but also made other
changes to get 6to4 working,  and no longer see panics.

Reverting the rule on a running system back to "ip", still yields
no panics, but I am now running a different 11.1 kernel built from
SVN with my "stf" patch.  So it is sadly not quite clear where the
problem was, my original configuration, the older kernel, something
else?

    # svn info
    Path: .
    Working Copy Root Path: /usr/src
    URL: https://svn0.us-west.freebsd.org/base/releng/11.1
    Relative URL: ^/releng/11.1
    Repository Root: https://svn0.us-west.freebsd.org/base
    Repository UUID: ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
    Revision: 325169
    Node Kind: directory
    Schedule: normal
    Last Changed Author: gordon
    Last Changed Rev: 324708
    Last Changed Date: 2017-10-17 17:20:07 -0400 (Tue, 17 Oct 2017)

-- 
	Viktor.