On Thu, Feb 8, 2018 at 12:01 AM, Florian Westphal <fw@xxxxxxxxx> wrote:
> Cong Wang <xiyou.wangcong@xxxxxxxxx> 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.
>>
>> Fixes: d73f33b16883 ("netfilter: CLUSTERIP: RCU conversion")
>> Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx>
>> Cc: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
>> Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
>> ---
>> net/ipv4/netfilter/ipt_CLUSTERIP.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
>> index 1ff72b87a066..4537b1686c7c 100644
>> --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
>> +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
>> @@ -154,8 +154,10 @@ 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)))
>
> this needs to call clusterip_config_put(c); too, else we leak one
> reference.
>
> Other than that this looks good.
Right, good catch! I will send v2.
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