Re: [mpls-linux-general] Crash in getifaddrs() when using a mpls-enabled kernel

[Vincent U. <vin...@im...>]

I found the problem. I'll follow up on mpls-linux-devel since it will
probably involve code rework...

Le lundi 18 avril 2005 =C3=A0 21:02 +0200, Vincent Untz a =C3=A9crit :
> No : it's just crashing before it can do anything.
>=20
> When tcpdump starts, it looks for available interfaces by calling
> getifaddrs() to know on what interfaces it can listen. This call crashs
> if I've setup an ilm and does not crash if there's no ilm.
>=20
> There's absolutely no traffic occuring during my test. The crash is also
> reproducable with a small program that just calls getifaddrs().
>=20
> I've tried to debug this and it seems that getifaddrs() uses netlink to
> get the interfaces in glibc >=3D 2.3.3. And there's a bogus netlink
> RTM_NEWADDR (IIRC) message that is received when the crash is happening
> (the interface index is wrong, with a value like 6323421!).
>=20
> I don't know if it's a bug in mpls or in the glibc since 'ip link show'
> does not crash (and it uses netlink to get the list of interfaces
> too)...
>=20
> Le lundi 18 avril 2005 =C3=A0 13:06 -0500, James R. Leu a =C3=A9crit :
> > If I understand correctly, you're saying that tcpdump is crashing when
> > it tries to decode MPLS packets on the receive side?
> >=20
> > On Mon, Apr 18, 2005 at 02:19:21PM +0200, Vincent Untz wrote:
> > > Hi,
> > >=20
> > > I'm experiencing the problem described in
> > > http://sourceforge.net/mailarchive/forum.php?thread_id=3D6272612&foru=
m_id=3D5051
> > >=20
> > > In order to make sure I was not doing something wrong, I installed a
> > > stock fedora core 2, used the rpm provided on the mpls-linux project
> > > page.
> > >=20
> > > Here are the steps to reproduce the crash:
> > >=20
> > > [root@tom3 root]# cat /sys/mpls/version
> > > 1.946
> > > [root@tom3 root]# mpls labelspace add dev eth0 labelspace 0
> > > [root@tom3 root]# mpls ilm add label gen 10000 labelspace 0
> > > [root@tom3 root]# mpls ilm show
> > > ILM entry label gen 10000 labelspace 0 proto ipv4
> > >         pop peek  (0 bytes, 0 pkts, 0 dropped)
> > > [root@tom3 root]# tcpdump
> > > Aborted
> > > [root@tom3 root]# tcpdump -i eth0
> > > tcpdump: verbose output suppressed, use -v or -vv for full protocol d=
ecode
> > > listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
> > > ...
> > > [root@tom3 root]# mpls ilm del label gen 10000 labelspace 0
> > > [root@tom3 root]# tcpdump
> > > tcpdump: verbose output suppressed, use -v or -vv for full protocol d=
ecode
> > > listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
> > > ...
> > >=20
> > > Here's a stack trace:
> > > (gdb) bt
> > > #0  0xffffe410 in ?? ()
> > > #1  0xbffff5b8 in ?? ()
> > > #2  0x00000006 in ?? ()
> > > #3  0x00000c9e in ?? ()
> > > #4  0xb7eebe59 in raise () from /lib/tls/libc.so.6
> > > #5  0xb7eed882 in abort () from /lib/tls/libc.so.6
> > > #6  0xb7f9d3fb in getifaddrs () from /lib/tls/libc.so.6
> > > #7  0x0808bedd in error ()
> > > #8  0x0808d0b9 in pcap_setnonblock_fd ()
> > > #9  0x08081264 in ?? ()
> > > #10 0xbffff8c0 in ?? ()
> > > #11 0xbffffa74 in ?? ()
> > > #12 0x080b14a8 in _IO_stdin_used ()
> > > #13 0x00000000 in ?? ()
> > >=20
> > > I can always reproduce this. Is there anything I can do to help?
> > >=20
> > > Thanks,
> > >=20
> > > Vincent
> > >=20
> > > --=20
> > > Les gens heureux ne sont pas press??s.
> >=20
> >=20
> >=20
> Vincent
>=20

Vincent

--=20
Les gens heureux ne sont pas press=C3=A9s.