segfaults when system has >32 interfaces about pim6sd HOT 5 CLOSED

Ok, an error in the external call to syslog() seemed very suspicous and a bug in there quite unlikely.

So my suspicion was that there is probably some stack corruption earlier. And adding some printf()s often moved the segfault to other locations.

It seems that there is some length check missing for v = &uvifs[numvifs++]; in find_vif()s. uvifs has MAXMIFS = 32 elements and I have more than 32 interfaces. With an added printf() I could confirm that find_vif() increased numvifs to 37 and returned the non-existent &uvifs[37] shortly before crashing.

Disabling interfaces via "phyint <iface> disable;" in the config file does not help as it seems that find_vif() is called for all interfaces regardless of their usage.

I guess back in 2001 people thought no one would ever have more than 32 interfaces on a single system :-).

from pim6sd.

Heh, classic. I fixed this in pimd over ten years ago 😆 ... oh how this little puppy need some tender love and care.

I'll look into fixing this bug later today (after work) when I'll port the pimd --disable-vifs from #4.

from pim6sd.

There, with the discovery in #4 and fixes on master you should be set to go. Thank you for taking the time to test pim6sd!

from pim6sd.

Yes, works great! I can't reproduce any segmentation faults with this patch. Thanks a lot ❤️!

(One thing I noticed is that having >32 "phyint <iface> disabled;" statements still gives an error on startup. However just using "default_phyint_status disable;" and enabling the two interfaces I need works just fine.)

Also thanks a lot for your swiftness and help with everything 😃. (I hope @mweinelt and I are not causing any inconveniences. From our side, no need for hurry ☺️)

from pim6sd.

Cool, good to hear the fix worked! :)

The code really needs more attention, there are too many assumptions that should be explicitly checked and warnings added. I recognize much of it from my restoration of pimd, so bear with me.

No problem, just happy to help out. Really great to have a couple of knowledgeable testers trying things out. I have a couple of other projects that also need attention, but I'm taking this one as a great opportunity to learn IPv6 :-)

from pim6sd.