Commit 04e4a11d authored by Florian Westphal's avatar Florian Westphal Committed by Greg Kroah-Hartman
Browse files

netfilter: conntrack: re-fetch conntrack after insertion 



commit 56b14ece upstream.

In case the conntrack is clashing, insertion can free skb->_nfct and
set skb->_nfct to the already-confirmed entry.

This wasn't found before because the conntrack entry and the extension
space used to free'd after an rcu grace period, plus the race needs
events enabled to trigger.

Reported-by: default avatar <syzbot+793a590957d9c1b96620@syzkaller.appspotmail.com>
Fixes: 71d8c47f ("netfilter: conntrack: introduce clash resolution on insertion race")
Fixes: 2ad9d774 ("netfilter: conntrack: free extension area immediately")
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 86c0154f

include/net/netfilter/nf_conntrack_core.h

+6 −1
Original line number Diff line number Diff line
@@ -58,8 +58,13 @@ static inline int nf_conntrack_confirm(struct sk_buff *skb) 
	int ret = NF_ACCEPT;



	if (ct) {

		if (!nf_ct_is_confirmed(ct))

		if (!nf_ct_is_confirmed(ct)) {

			ret = __nf_conntrack_confirm(skb);



			if (ret == NF_ACCEPT)

				ct = (struct nf_conn *)skb_nfct(skb);

		}



		if (likely(ret == NF_ACCEPT))

			nf_ct_deliver_cached_events(ct);

	}