Panic in imo_match_source (netinet/in_mcast.c)

[Shteryana Shopova]

Hi,

I actually managed to get the same kernel dump using the following
sample code - http://people.freebsd.org/~syrinx/mcast/mcast_crash.c
and the crash is 100% reproducable. A temporary fix is here -
http://people.freebsd.org/~syrinx/mcast/in_mcast.c-20090908-01.diff
but I actually prefer that we go over the logic in inp_join_group()
again before proposing a patch for head as this is the second assert
panic I am seeing it causes in the last few days. I can try making up
a proper fix if Bruce is busy, but it will take a day or two until I'm
able to fully test it.

cheers,
Shteryana

On Tue, Sep 8, 2009 at 4:13 PM, Bruce Simpson<bms at incunabulum.net> wrote:
> [Brief reply as I'm meant to be doing a zillion other things...]
>
> Bruce Simpson wrote:
>>
>> Full OS version, dmesg, panic and backtrace please, when reporting this
>> kind of issue... otherwise folk can't help. Are you using SSM multicast
>> features?
>
> P.S. You might want to try demoting the KASSERT to a conditional error
> return (return no match if src is NULL or src->sa_family != AF_INET), and
> see if that fix 'just works' for you. Sometimes the asserts I sprinkle into
> code are too paranoid for what's going on, and syrinx@ recently caught one
> of those.
>
> I can see some situations where this could kick off, so that is probably the
> right fix. Please do let me know. If that fix works for you then it can
> probably be checked in. There is an RC cutoff looming, so if I can't do it
> in time, someone else may be able to check it in.
>
> thanks,
> BMS
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