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net: avoid reference counter overflows on fib_rules in multicast forwarding

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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: f0ad0860d0 ("ipv4: ipmr: support multiple tables")
Fixes: d1db275dd3 ("ipv6: ip6mr: support multiple tables")
Reported-by: Bob Falken <[email protected]>
Cc: Patrick McHardy <[email protected]>
Cc: Thomas Graf <[email protected]>
Cc: Julian Anastasov <[email protected]>
Cc: Eric Dumazet <[email protected]>
Signed-off-by: Hannes Frederic Sowa <[email protected]>
Acked-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
This commit is contained in:
Hannes Frederic Sowa 2014-01-13 02:45:22 +01:00 • committed by David S. Miller
commit 95f4a45de1
2 changed files with 10 additions and 4 deletions
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7
net/ipv6/ip6mr.c
View file

@ -141,9 +141,12 @@ static struct mr6_table *ip6mr_get_table(struct net *net, u32 id)
static int ip6mr_fib_lookup(struct net *net, struct flowi6 *flp6,
struct mr6_table **mrt)
{
struct ip6mr_result res;
struct fib_lookup_arg arg = { .result = &res, };
int err;
struct ip6mr_result res;
struct fib_lookup_arg arg = {
.result = &res,
.flags = FIB_LOOKUP_NOREF,
};
err = fib_rules_lookup(net->ipv6.mr6_rules_ops,
flowi6_to_flowi(flp6), 0, &arg);