From 95f4a45de1a0f172b35451fc52283290adb21f6e Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Mon, 13 Jan 2014 02:45:22 +0100 Subject: net: avoid reference counter overflows on fib_rules in multicast forwarding 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 Cc: Patrick McHardy Cc: Thomas Graf Cc: Julian Anastasov Cc: Eric Dumazet Signed-off-by: Hannes Frederic Sowa Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/ipmr.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'net/ipv4/ipmr.c') diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c index 62212c772a4b..1672409f5ba5 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -157,9 +157,12 @@ static struct mr_table *ipmr_get_table(struct net *net, u32 id) static int ipmr_fib_lookup(struct net *net, struct flowi4 *flp4, struct mr_table **mrt) { - struct ipmr_result res; - struct fib_lookup_arg arg = { .result = &res, }; int err; + struct ipmr_result res; + struct fib_lookup_arg arg = { + .result = &res, + .flags = FIB_LOOKUP_NOREF, + }; err = fib_rules_lookup(net->ipv4.mr_rules_ops, flowi4_to_flowi(flp4), 0, &arg); -- cgit v1.2.3-59-g8ed1b