first (?) bird 3.0.0 bug report

[Maria Matejka]

Hello Alarig,

this was indeed a problem (and there was some more to fix) and if
I haven't missed anything (but it now looks OK for me), here is a fixed
version: <https://gitlab.nic.cz/labs/bird/-/commit/2e14832d36c83b2ab5b7fb28b701de554fa5fdd9>

If you could check that it works for you as well, it would be very helpful.

Thank you for your report! 
Maria

On Tue, Dec 31, 2024 at 10:05:12AM +0100, Alarig Le Lay via Bird-users wrote:

> I read the coredump (and the source code) with a fresh cup of coffee,
> and acted accordingly:
> 
> The error is there:
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0  0x000055861e8cb989 in bgp_rte_recalculate (table=0x55861fe0a250, net=0x55861fe1b320, new_stored=0x7f13aaedd070, old_stored=0x0, old_best_stored=0x0) at proto/bgp/attrs.c:2696
> 
> Which corresponds to the deterministic med:
> https://gitlab.nic.cz/labs/bird/-/blob/v3.0.0/proto/bgp/attrs.c?ref_type=tags#L2696
>   int old_suppressed = old ? !!(old->pflags & BGP_REF_SUPPRESSED) : 0;
> 
> To be used there:
> https://gitlab.nic.cz/labs/bird/-/blob/v3.0.0/proto/bgp/attrs.c?ref_type=tags#L2455
>   n = new->pflags & BGP_REF_SUPPRESSED;
>   o = old->pflags & BGP_REF_SUPPRESSED;
> 
> So I commented it and now bird starts:
> rr3 ~ # grep med /etc/bird.conf
> 	med metric on;
> 	#deterministic med on;
> 	med metric on;
> 	#deterministic med on;
> 
> On Mon 30 Dec 2024 22:35:02 GMT, Alarig Le Lay wrote:
> 
> > Hello David,
> > 
> > Here is the coredump: https://herbizarre.swordarmor.fr/garbage/core-bird.29074.rr3.swordarmor.fr.1735592879
> > And here is the config: https://herbizarre.swordarmor.fr/garbage/bird.conf.29074.rr3.swordarmor.fr.1735592879
> > 
> > I compiled bird3 with the two previous patches of this ML:
> > 
> >  * Applying bird-3.0.0-nest-rt-table.c.patch ...
> >  * Applying bird-3.0.0-proto-lock.patch ...
> > 
> > And I enabled the debug:
> > 
> > ./configure --prefix=/usr --build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu --mandir=/usr/share/man --infodir=/usr/share/info --datadir=/usr/share --sysconfdir=/etc --localstatedir=/var/lib --datarootdir=/usr/share --docdir=/usr/share/doc/bird-3.0.0 --htmldir=/usr/share/doc/bird-3.0.0/html --libdir=/usr/lib64 --localstatedir=/var --enable-client --enable-debug --disable-libssh
> > 
> > So I have a different trace in dmesg (I supposed that it’s due to having
> > debug symbols):
> > [1305799.952226] bird[29075]: segfault at 8 ip 000055861e8cb989 sp 00007f13ab6e0b40 error 4 in bird[55861e7ed000+15c000]
> > [1305799.952251] Code: 89 c7 e8 13 80 ff ff 89 85 6c ff ff ff 48 8b 45 c0 48 89 c7 e8 2d f3 ff ff 89 85 70 ff ff ff 48 83 7d b0 00 74 18 48 8b 45 b0 <0f> b6 00 0f b6 c0 83 e0 01 85 c0 74 07 b8 01 00 00 00 eb 05 b8 00
> > 
> > Regarding the setup, I don’t think that it’s that unconventional, but
> > it’s a RR outside of the network (it’s on my own network which is pretty
> > much experimental, so I experiment). I noticed that I never removed the
> > OSPF from the kernel filters until now, but even with 'export none' I
> > still get the crash.
> > 
> > So I then tried to enable all the debug options:
> > rr3 ~ # grep debug /etc/bird.conf
> > debug protocols all;
> > debug channels all;
> > debug tables all;
> > 
> > And here are the logs: https://paste.swordarmor.fr/raw/Owej
> > 
> > I hope it’s useful, don’t hesitate to ask me if you need anything else.
> > 
> > Happy new year to you too!
> > Alarig
> > 
> > On Mon 30 Dec 2024 16:49:41 GMT, David Petera wrote:
> > 
> > > Hello Alarig,
> > > 
> > > thanks for reporting!
> > > 
> > > The coredump and config would be much appreciated, so I can try to 
> > > reproduce it.
> > > Also would you say there is something unconventional about the said 
> > > setup that might be causing the problem?
> > > 
> > > Thanks in advance and happy new year,
> > > 
> > > David
> > > 
> > > On 12/19/24 19:16, Alarig Le Lay via Bird-users wrote:
> > > 
> > > > Hello Maria,
> > > >
> > > > I thought that I had the same bug, but it seems that it’s a different
> > > > one as I applied the patch but I still got a segfault at startup.
> > > >
> > > > [342115.227497] bird[19396]: segfault at 8 ip 00005642c37062db sp 00007fc784295ca0 error 4 in bird[5642c366e000+f0000]
> > > > [342115.227524] Code: 39 10 0f 85 e3 8c f6 ff 48 8b 90 b0 01 00 00 8b 8a 10 01 00 00 89 4c 24 24 85 c9 0f 84 d6 00 00 00 4d 85 ff 0f 84 e0 00 00 00 <41> 0f b6 44 24 08 89 c2 83 e2 01 4d 85 ed 75 15 83 c8 01 41 88 44
> > > >
> > > > I can generate a coredump and share my configuration if needed.
> > > >
> > > > Alarig
> > > >
> > > > [...]

-- 
Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.
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