From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cong Wang Subject: [Patch net v2] ipt_CLUSTERIP: fix a refcount bug in clusterip_config_find_get() Date: Thu, 8 Feb 2018 13:53:52 -0800 Message-ID: <20180208215352.8294-1-xiyou.wangcong@gmail.com> Cc: netfilter-devel@vger.kernel.org, pabeni@redhat.com, Cong Wang , Eric Dumazet , Pablo Neira Ayuso , Florian Westphal To: netdev@vger.kernel.org Return-path: Sender: netdev-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org 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 --- net/ipv4/netfilter/ipt_CLUSTERIP.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) 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(); -- 2.13.0