linux-kernel - [PATCH 3.13 059/212] batman-adv: increase orig refcount when storing ref in gw

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Date:	Tue, 17 Jun 2014 14:42:33 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Antonio Quartulli <antonio@...n-mesh.com>,
	Marek Lindner <mareklindner@...mailbox.ch>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13 059/212] batman-adv: increase orig refcount when storing ref in gw_node

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

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

From: Antonio Quartulli <antonio@...n-mesh.com>

[ Upstream commit 377fe0f968b30a1a714fab53a908061914f30e26 ]

A pointer to the orig_node representing a bat-gateway is
stored in the gw_node->orig_node member, but the refcount
for such orig_node is never increased.
This leads to memory faults when gw_node->orig_node is accessed
and the originator has already been freed.

Fix this by increasing the refcount on gw_node creation
and decreasing it on gw_node free.

Signed-off-by: Antonio Quartulli <antonio@...n-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@...mailbox.ch>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 net/batman-adv/gateway_client.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index 2449afa..68676cd 100644
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -38,8 +38,10 @@
 
 static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node)
 {
-	if (atomic_dec_and_test(&gw_node->refcount))
+	if (atomic_dec_and_test(&gw_node->refcount)) {
+		batadv_orig_node_free_ref(gw_node->orig_node);
 		kfree_rcu(gw_node, rcu);
+	}
 }
 
 static struct batadv_gw_node *
@@ -351,9 +353,14 @@ static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 	if (gateway->bandwidth_down == 0)
 		return;
 
+	if (!atomic_inc_not_zero(&orig_node->refcount))
+		return;
+
 	gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
-	if (!gw_node)
+	if (!gw_node) {
+		batadv_orig_node_free_ref(orig_node);
 		return;
+	}
 
 	INIT_HLIST_NODE(&gw_node->list);
 	gw_node->orig_node = orig_node;
-- 
1.9.1

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