Cong Wang <xiyou.wangc...@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.
> 
> Fixes: d73f33b16883 ("netfilter: CLUSTERIP: RCU conversion")
> Cc: Eric Dumazet <eric.duma...@gmail.com>
> Cc: Pablo Neira Ayuso <pa...@netfilter.org>
> Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
> ---
>  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.
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