From db93a3632b0f8773a3899e04a3a3e0aa7a26eb46 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Thu, 8 Feb 2018 13:53:52 -0800 Subject: netfilter: ipt_CLUSTERIP: fix a refcount bug in clusterip_config_find_get() In clusterip_config_find_get() we hold RCU read lock so it could run concurrently with clusterip_config_entry_put(), as a result, the refcnt could go back to 1 from 0, which leads to a double list_del()... Just replace refcount_inc() with refcount_inc_not_zero(), as for c->refcount. Fixes: d73f33b16883 ("netfilter: CLUSTERIP: RCU conversion") Cc: Eric Dumazet Cc: Pablo Neira Ayuso Cc: Florian Westphal Signed-off-by: Cong Wang Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/ipt_CLUSTERIP.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'net/ipv4/netfilter') diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c index 1ff72b87a066..4b02ab39ebc5 100644 --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c @@ -154,8 +154,12 @@ clusterip_config_find_get(struct net *net, __be32 clusterip, int entry) #endif if (unlikely(!refcount_inc_not_zero(&c->refcount))) c = NULL; - else if (entry) - refcount_inc(&c->entries); + else if (entry) { + if (unlikely(!refcount_inc_not_zero(&c->entries))) { + clusterip_config_put(c); + c = NULL; + } + } } rcu_read_unlock_bh(); -- cgit v1.2.3