netdev - Re: [PATCH net v2] bridge: fix multicast router rlist endless loop

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Message-ID: <20150610022231.GA32260@gondor.apana.org.au>
Date:	Wed, 10 Jun 2015 10:22:31 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net,
	stephen@...workplumber.org,
	Nikolay Aleksandrov <razor@...ckwall.org>
Subject: Re: [PATCH net v2] bridge: fix multicast router rlist endless loop

On Tue, Jun 09, 2015 at 10:23:57AM -0700, Nikolay Aleksandrov wrote:
> From: Nikolay Aleksandrov <razor@...ckwall.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 adding a check in br_multicast_add_router() if the port is
> already linked.
> 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 <razor@...ckwall.org>
> Fixes: 0909e11758bd ("bridge: Add multicast_router sysfs entries")

Acked-by: Herbert Xu <herbert@...dor.apana.org.au>
-- 
Email: Herbert Xu <herbert@...dor.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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