On Tue, Jun 09, 2015 at 02:32:28AM -0700, Nikolay Aleksandrov wrote:
> From: Nikolay Aleksandrov <ra...@blackwall.org>
>
> Since the addition of sysfs multicast router support if one set
> multicast_router to "2" more than once, then the port would be added to the
> hlist every time and could end up linking to itself and thus causing an
> endless loop for rlist walkers.
> So to reproduce just do:
> echo 2 > multicast_router; echo 2 > multicast_router;
> in a bridge port and let some igmp traffic flow, for me it hangs up
> in br_multicast_flood().
> Fix this by removing the "val < 2" check, and just do the hlist_del
> always.
> We can remove the "!hlist_unhashed" check because it's already done by
> hlist_del_init_rcu(), in fact this can also be done for
> br_multicast_disable_port() but that is net-next material.
> The reason this didn't happen before the addition of multicast_router
> sysfs entries is because there's a !hlist_unhashed check that prevents
> it.
>
> Signed-off-by: Nikolay Aleksandrov <ra...@blackwall.org>
> Fixes: 0909e11758bd ("bridge: Add multicast_router sysfs entries")
Good catch!
> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
> index 22fd0419b314..ecdd13512320 100644
> --- a/net/bridge/br_multicast.c
> +++ b/net/bridge/br_multicast.c
> @@ -1993,8 +1993,7 @@ int br_multicast_set_port_router(struct net_bridge_port
> *p, unsigned long val)
> p->multicast_router = val;
> err = 0;
>
> - if (val < 2 && !hlist_unhashed(&p->rlist))
> - hlist_del_init_rcu(&p->rlist);
> + hlist_del_init_rcu(&p->rlist);
This should work but removing it and readding seems strange.
How about moving the hlist_unhashed test that's currently in
br_multicast_mark_router into br_multicast_add_router instead?
Thanks,
--
Email: Herbert Xu <herb...@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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