[PATCH 3.16 022/306] netfilter: restart search if moved to other chain

[Ben Hutchings]

3.16.40-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Florian Westphal <fw@xxxxxxxxx>

commit 95a8d19f28e6b29377a880c6264391a62e07fccc upstream.

In case nf_conntrack_tuple_taken did not find a conflicting entry
check that all entries in this hash slot were tested and restart
in case an entry was moved to another chain.

Reported-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Fixes: ea781f197d6a ("netfilter: nf_conntrack: use SLAB_DESTROY_BY_RCU and get rid of call_rcu()")
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
[bwh: Backported to 3.16:
 - Adjust context
 - Use NF_CT_STAT_INC(), not the _ATOMIC variant, since we disable BHs]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/netfilter/nf_conntrack_core.c | 7 +++++++
 1 file changed, 7 insertions(+)

--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -726,6 +726,7 @@ nf_conntrack_tuple_taken(const struct nf
 	 * least once for the stats anyway.
 	 */
 	rcu_read_lock_bh();
+ begin:
 	hlist_nulls_for_each_entry_rcu(h, n, &net->ct.hash[hash], hnnode) {
 		ct = nf_ct_tuplehash_to_ctrack(h);
 		if (ct != ignored_conntrack &&
@@ -737,6 +738,12 @@ nf_conntrack_tuple_taken(const struct nf
 		}
 		NF_CT_STAT_INC(net, searched);
 	}
+
+	if (get_nulls_value(n) != hash) {
+		NF_CT_STAT_INC(net, search_restart);
+		goto begin;
+	}
+
 	rcu_read_unlock_bh();
 
 	return 0;