Subject: Re: [PATCH] netfilter: nf_conntrack: fix RCU race in nf_conntrack_find_get

From: Florian Westphal <[email-masked]>
Date: Thu, 9 Jan 2014 21:56:22 +0100

Andrew Vagin <[email-masked]> wrote:
> Can we allocate conntrack with zero ct_general.use and increment it at
> the first time before inserting the conntrack into the hash table?
> When conntrack is allocated it is attached exclusively to one skb.
> It must be destroyed with skb, if it has not been confirmed, so we
> don't need refcnt on this stage.
> 
> I found only one place, where a reference counter of unconfirmed
> conntract can incremented. It's ctnetlink_dump_table().

What about skb_clone, etc?  They will also increment the refcnt
if a conntrack entry is attached to the skb.