linux-kernel - [PATCH 3.16.y-ckt 166/180] batman-adv: fix potential TT client + orig-node memory leak

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Message-Id: <1454538786-12215-167-git-send-email-luis.henriques@canonical.com>
Date:	Wed,  3 Feb 2016 22:32:52 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Linus Lüssing <linus.luessing@...3.blue>,
	Marek Lindner <mareklindner@...mailbox.ch>,
	Antonio Quartulli <antonio@...hcoding.com>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 166/180] batman-adv: fix potential TT client + orig-node memory leak

3.16.7-ckt24 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@...3.blue>

commit 9d31b3ce81683ce3c9fd10afa70892e373b21067 upstream.

This patch fixes a potential memory leak which can occur once an
originator times out. On timeout the according global translation table
entry might not get purged correctly. Furthermore, the non purged TT
entry will cause its orig-node to leak, too. Which additionally can lead
to the new multicast optimization feature not kicking in because of a
therefore bogus counter.

In detail: The batadv_tt_global_entry->orig_list holds the reference to
the orig-node. Usually this reference is released after
BATADV_PURGE_TIMEOUT through: _batadv_purge_orig()->
batadv_purge_orig_node()->batadv_update_route()->_batadv_update_route()->
batadv_tt_global_del_orig() which purges this global tt entry and
releases the reference to the orig-node.

However, if between two batadv_purge_orig_node() calls the orig-node
timeout grew to 2*BATADV_PURGE_TIMEOUT then this call path isn't
reached. Instead the according orig-node is removed from the
originator hash in _batadv_purge_orig(), the batadv_update_route()
part is skipped and won't be reached anymore.

Fixing the issue by moving batadv_tt_global_del_orig() out of the rcu
callback.

Signed-off-by: Linus Lüssing <linus.luessing@...3.blue>
Acked-by: Antonio Quartulli <antonio@...hcoding.com>
Signed-off-by: Marek Lindner <mareklindner@...mailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@...hcoding.com>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 net/batman-adv/originator.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 57b30a6b9bbb..e4eeb6342b38 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -570,9 +570,6 @@ static void batadv_orig_node_free_rcu(struct rcu_head *rcu)

 	batadv_frag_purge_orig(orig_node, NULL);

-	batadv_tt_global_del_orig(orig_node->bat_priv, orig_node, -1,
-				  "originator timed out");
-
 	if (orig_node->bat_priv->bat_algo_ops->bat_orig_free)
 		orig_node->bat_priv->bat_algo_ops->bat_orig_free(orig_node);

@@ -982,6 +979,9 @@ static void _batadv_purge_orig(struct batadv_priv *bat_priv)
 			if (batadv_purge_orig_node(bat_priv, orig_node)) {
 				batadv_gw_node_delete(bat_priv, orig_node);
 				hlist_del_rcu(&orig_node->hash_entry);
+				batadv_tt_global_del_orig(orig_node->bat_priv,
+							  orig_node, -1,
+							  "originator timed out");
 				batadv_orig_node_free_ref(orig_node);
 				continue;
 			}