3.16.57-rc1 review patch. If anyone has any objections, please let me know.
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From: Cong Wang xiyou.wangcong@gmail.com
commit db93a3632b0f8773a3899e04a3a3e0aa7a26eb46 upstream.
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 eric.dumazet@gmail.com Cc: Pablo Neira Ayuso pablo@netfilter.org Cc: Florian Westphal fw@strlen.de Signed-off-by: Cong Wang xiyou.wangcong@gmail.com Reviewed-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org [bwh: Backported to 3.16: s/refcount/atomic/] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- net/ipv4/netfilter/ipt_CLUSTERIP.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c @@ -147,8 +147,12 @@ clusterip_config_find_get(struct net *ne if (c) { if (unlikely(!atomic_inc_not_zero(&c->refcount))) c = NULL; - else if (entry) - atomic_inc(&c->entries); + else if (entry) { + if (unlikely(!atomic_inc_not_zero(&c->entries))) { + clusterip_config_put(c); + c = NULL; + } + } } rcu_read_unlock_bh();