From: Tom Smyth <tom.smyth@wirelessconnect.eu>
Subject: Re: bgpd: properly discard pfkey error messages
To: tech@openbsd.org
Date: Sun, 14 Sep 2025 02:25:32 +0100

Folks

Just to confirm I tested the diff  on OPENBSD_7_7 branch and applied
the path and it worked as advertised,

mind you I had to do a kill -9  to stop the bgpd process ,

I have installed this on all my affected BGP / nsh boxes and they seem
to be working well

Thanks  again

Tom Smyth

On Fri, 12 Sept 2025 at 13:00, Tom Smyth <tom.smyth@wirelessconnect.eu> wrote:
>
> Hi Theo, Claudio
> Thanks for fix diff and the review.
>
> Much obliged,
> Tom Smyth
>
>
> On Fri, 12 Sept 2025 at 12:44, Theo Buehler <tb@theobuehler.org> wrote:
> >
> > On Fri, Sep 12, 2025 at 01:34:34PM +0200, Claudio Jeker wrote:
> > > pfkey_reply() needs to discard any error message (including those for
> > > ESRCH). The fix I did in 1.64 was not quite right since for the ESRCH
> > > case the message remained in the socket and that results into a busy
> > > loop in the bgpd main event loop since a ESRCH message is newer flushed
> > > from the socket.
> > >
> > > This is a fix for the busy loop Tom Smyth reported on bugs@.
> > > Thanks to Tom for providing me with a ktrace of bgpd that made me find the
> > > bug in less than 5min.
> >
> > Fortunately the diff is as easy to review as it was to find the fix.
> > Definitely looks like something a diligent reviewer might've caught...
> >
> > ok tb
> >
> > > --
> > > :wq Claudio
> > >
> > > Index: pfkey.c
> > > ===================================================================
> > > RCS file: /cvs/src/usr.sbin/bgpd/pfkey.c,v
> > > diff -u -p -r1.72 pfkey.c
> > > --- pfkey.c   27 Feb 2025 14:03:32 -0000      1.72
> > > +++ pfkey.c   12 Sep 2025 11:27:44 -0000
> > > @@ -453,13 +453,15 @@ pfkey_reply(int sd, uint32_t *spi)
> > >
> > >       if (hdr.sadb_msg_errno != 0) {
> > >               errno = hdr.sadb_msg_errno;
> > > +
> > > +             /* discard error message */
> > > +             if (read(sd, &hdr, sizeof(hdr)) == -1)
> > > +                     log_warn("pfkey read");
> > > +
> > >               if (errno == ESRCH)
> > >                       return (0);
> > >               else {
> > >                       log_warn("pfkey");
> > > -                     /* discard error message */
> > > -                     if (read(sd, &hdr, sizeof(hdr)) == -1)
> > > -                             log_warn("pfkey read");
> > >                       return (-1);
> > >               }
> > >       }
> > >
> >
>
>
> --
> Kindest regards,
> Tom Smyth.



-- 
Kindest regards,
Tom Smyth.