Re: 2.6 - Kernel panic with GRE tunneling

[Catalin BOIE]

> Hello,
Hello!

> I encountered some kernel bug in the ip_gre module. This problem has
> been tested on: 2.6.0-test3, 2.6.0-test4-mm2, 2.6.0-test4-mm4 (In VMWare
> to get stacktrace).
>
> All kernels were build with gcc 3.3 (the latest with 3.3.2 20030831
> Debian prerelease). Tested on 2 systems (one was a VMWare), both running
> Debian Sid.
>
> this is what I did:
>
> modprobe ip_gre
> ip tunnel add test mode gre remote 10.2.0.1 local 10.2.248.255
> ip link set test up
> ip addr add 192.168.0.1 dev test
> ip route add 192.168.0.2/32 dev test
> ping 192.168.0.2
> ***crash***
>
> In order to limit the e-mail's size:
> http://brains.student.utwente.nl/~iq-0/ipgre-2.6-panic/
> there are the paniclog, an attempt to run it through ksymoops and a
> tcpdump.
>
> *note: In this test case I didn't set up the other end-point of the
> tunnel (because the other system is also 2.6 ;), but on a real life
> tunnel the same thing happened. But one doesn't liketo crash his/her
> system more than 10 times a week...
>
> Regards,
>
> justin....

I investigated a little and seems that in ip_gre.c, in
function ipgre_tunnel_lookup, at the end there is the code:

if (ipgre_fb_tunnel_dev->flags&IFF_UP)
	return ipgre_fb_tunnel_dev->priv;

Seems that ipgre_fb_tunnel_dev is NULL!

ipgre_fb_tunnel_dev is initialized in ipgre_init.

Some net guys call tell why ipgre_fb_tunnel_dev is still NULL after init.

I bet that if you configure the tunnels on both machines, it works.

Can you reproduce this without VMware?

---
Catalin(ux) BOIE
catab@xxxxxxxxxxxxxxx
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