linux-kernel - [PATCH 4.4 35/74] netfilter: restart search if moved to other chain

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Date:   Mon, 29 Jan 2018 13:56:40 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        Florian Westphal <fw@...len.de>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Michal Kubecek <mkubecek@...e.cz>
Subject: [PATCH 4.4 35/74] netfilter: restart search if moved to other chain

4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Florian Westphal <fw@...len.de>

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@...gle.com>
Fixes: ea781f197d6a ("netfilter: nf_conntrack: use SLAB_DESTROY_BY_RCU and get rid of call_rcu()")
Signed-off-by: Florian Westphal <fw@...len.de>
Acked-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Acked-by: Michal Kubecek <mkubecek@...e.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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
@@ -719,6 +719,7 @@ 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 &&
@@ -730,6 +731,12 @@ 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;