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Message-Id: <20140114.174046.2032110531064031820.davem@davemloft.net>
Date: Tue, 14 Jan 2014 17:40:46 -0800 (PST)
From: David Miller <davem@...emloft.net>
To: hannes@...essinduktion.org
Cc: eric.dumazet@...il.com, NetFestivalHaveFun@....com, ja@....bg,
netdev@...r.kernel.org, kaber@...sh.net, tgraf@...g.ch
Subject: Re: [PATCH net] net: avoid reference counter overflows on
fib_rules in multicast forwarding
From: Hannes Frederic Sowa <hannes@...essinduktion.org>
Date: Mon, 13 Jan 2014 02:45:22 +0100
> Bob Falken reported that after 4G packets, multicast forwarding stopped
> working. This was because of a rule reference counter overflow which
> freed the rule as soon as the overflow happend.
>
> This patch solves this by adding the FIB_LOOKUP_NOREF flag to
> fib_rules_lookup calls. This is safe even from non-rcu locked sections
> as in this case the flag only implies not taking a reference to the rule,
> which we don't need at all.
>
> Rules only hold references to the namespace, which are guaranteed to be
> available during the call of the non-rcu protected function reg_vif_xmit
> because of the interface reference which itself holds a reference to
> the net namespace.
>
> Fixes: f0ad0860d01e47 ("ipv4: ipmr: support multiple tables")
> Fixes: d1db275dd3f6e4 ("ipv6: ip6mr: support multiple tables")
> Reported-by: Bob Falken <NetFestivalHaveFun@....com>
> Cc: Patrick McHardy <kaber@...sh.net>
> Cc: Thomas Graf <tgraf@...g.ch>
> Cc: Julian Anastasov <ja@....bg>
> Cc: Eric Dumazet <eric.dumazet@...il.com>
> Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Applied and queued up for -stable, th anks.
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