| Message ID | 20180208215352.8294-1-xiyou.wangcong@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | Pablo Neira |
| Headers | show |
| Series | [net,v2] ipt_CLUSTERIP: fix a refcount bug in clusterip_config_find_get() | expand |
Cong Wang <xiyou.wangcong@gmail.com> wrote: > 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. Reviewed-by: Florian Westphal <fw@strlen.de> -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Feb 08, 2018 at 01:53:52PM -0800, Cong Wang wrote: > 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. Applied, thanks Cong. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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();
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> --- net/ipv4/netfilter/ipt_CLUSTERIP.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)