On Wed, Aug 07, 2013 at 06:27:19PM +0800, Gao feng wrote: > On 08/06/2013 09:19 PM, Pablo Neira Ayuso wrote: > > This patch adds the capability to attach expectations to unconfirmed > > conntrack entries. This patch is required by conntrack helpers that > > trigger expectations based on the first packet seen like the TFTP and > > the DHCPv6 user-space helpers. > > > > There is no need to bump the conntrack refcount since unconfirmed > > conntracks are not yet in the hashes, thus, they are just referenced > > by one single packet. There is no trouble either in the get_next_corpse > > path, as unconfirmed conntracks only get their dying bit set to > > be discarded later on by nf_conntrack_confirm. > > > > The use after free problem still may happen. > > the unconfirmed conntrack is created when we receive the first packet, > then this conntrack is linked in the per net global unconfirmed list. > > And this conntrack may be destroyed when the return value of l4proto->packet > low than 0 in nf_conntrack_in. I'm calling this from nfqueue, so the packet is retained until the user-space application issues the verdict on it, in that case that's not possible. But that interface is generic and to get this working in all cases, I need the bump the refcount. So you're right, I'm going to revamp this. Thanks for reviewing. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
