On Thu, Oct 31, 2013 at 09:13:32AM +0100, Daniel Borkmann wrote:
> Introduced in f9e42b853523 ("net: sctp: sideeffect: throw BUG if
> primary_path is NULL"), we intended to find a buggy assoc that's
> part of the assoc hash table with a primary_path that is NULL.
> However, we better remove the BUG_ON for now and find a more
> suitable place to assert for these things as Mark reports that
> this also triggers the bug when duplication cookie processing
> happens, and the assoc is not part of the hash table (so all
> good in this case). Such a situation can for example easily be
> reproduced by:
>
> tc qdisc add dev eth0 root handle 1: prio bands 2 priomap 1 1 1 1 1 1
> tc qdisc add dev eth0 parent 1:2 handle 20: netem loss 20%
> tc filter add dev eth0 protocol ip parent 1: prio 2 u32 match ip \
> protocol 132 0xff match u8 0x0b 0xff at 32 flowid 1:2
>
> This drops 20% of COOKIE-ACK packets. After some follow-up
> discussion with Vlad we came to the conclusion that for now we
> should still better remove this BUG_ON() assertion, and come up
> with two follow-ups later on, that is, i) find a more suitable
> place for this assertion, and possibly ii) have a special
> allocator/initializer for such kind of temporary assocs.
>
> Reported-by: Mark Thomas <Mark.Thomas@xxxxxxxxxxxxxx>
> Signed-off-by: Vlad Yasevich <vyasevich@xxxxxxxxx>
> Signed-off-by: Daniel Borkmann <dborkman@xxxxxxxxxx>
> ---
> net/sctp/sm_sideeffect.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
> index 666c668..1a6eef3 100644
> --- a/net/sctp/sm_sideeffect.c
> +++ b/net/sctp/sm_sideeffect.c
> @@ -860,7 +860,6 @@ static void sctp_cmd_delete_tcb(sctp_cmd_seq_t *cmds,
> (!asoc->temp) && (sk->sk_shutdown != SHUTDOWN_MASK))
> return;
>
> - BUG_ON(asoc->peer.primary_path == NULL);
> sctp_unhash_established(asoc);
> sctp_association_free(asoc);
> }
> --
> 1.8.3.1
>
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>
Acked-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
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