[PATCH net 06/15] batman-adv: v: prevent OGM aggregation on disabled hardif

[Simon Wunderlich <sw@simonwunderlich.de>]

From: Sven Eckelmann <sven@narfation.org>

When an interface gets disabled, the worker is correctly disabled by
batadv_hardif_disable_interface() -> ... -> batadv_v_ogm_iface_disable().
In this process, the skb aggr_list is also freed.

But batadv_v_ogm_send_meshif() can still queue new skbs (via
batadv_v_ogm_queue_on_if()) to the aggr_list. This will only stop after all
cores can no longer find the RCU protected list of hard interfaces. These
queued skbs will never be freed or consumed by batadv_v_ogm_aggr_work.

The batadv_v_ogm_iface_disable() function must block
batadv_v_ogm_queue_on_if() to avoid leak of skbs.

Cc: stable@kernel.org
Fixes: f89255a02f1d ("batman-adv: BATMAN_V: introduce per hard-iface OGMv2 queues")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/bat_v.c     |  1 +
 net/batman-adv/bat_v_ogm.c | 12 ++++++++++++
 net/batman-adv/types.h     |  6 ++++++
 3 files changed, 19 insertions(+)

diff --git a/net/batman-adv/bat_v.c b/net/batman-adv/bat_v.c
index fe7c0113d0df3..db6f5bdcaa985 100644
--- a/net/batman-adv/bat_v.c
+++ b/net/batman-adv/bat_v.c
@@ -817,6 +817,7 @@ void batadv_v_hardif_init(struct batadv_hard_iface *hard_iface)
 
 	hard_iface->bat_v.aggr_len = 0;
 	skb_queue_head_init(&hard_iface->bat_v.aggr_list);
+	hard_iface->bat_v.aggr_list_enabled = false;
 	INIT_DELAYED_WORK(&hard_iface->bat_v.aggr_wq,
 			  batadv_v_ogm_aggr_work);
 	/* make sure it doesn't run until interface gets enabled */
diff --git a/net/batman-adv/bat_v_ogm.c b/net/batman-adv/bat_v_ogm.c
index 81926ef9c02c9..95efd8a43c79d 100644
--- a/net/batman-adv/bat_v_ogm.c
+++ b/net/batman-adv/bat_v_ogm.c
@@ -254,11 +254,18 @@ static void batadv_v_ogm_queue_on_if(struct batadv_priv *bat_priv,
 	}
 
 	spin_lock_bh(&hard_iface->bat_v.aggr_list.lock);
+	if (!hard_iface->bat_v.aggr_list_enabled) {
+		kfree_skb(skb);
+		goto unlock;
+	}
+
 	if (!batadv_v_ogm_queue_left(skb, hard_iface))
 		batadv_v_ogm_aggr_send(bat_priv, hard_iface);
 
 	hard_iface->bat_v.aggr_len += batadv_v_ogm_len(skb);
 	__skb_queue_tail(&hard_iface->bat_v.aggr_list, skb);
+
+unlock:
 	spin_unlock_bh(&hard_iface->bat_v.aggr_list.lock);
 }
 
@@ -415,6 +422,10 @@ int batadv_v_ogm_iface_enable(struct batadv_hard_iface *hard_iface)
 {
 	struct batadv_priv *bat_priv = netdev_priv(hard_iface->mesh_iface);
 
+	spin_lock_bh(&hard_iface->bat_v.aggr_list.lock);
+	hard_iface->bat_v.aggr_list_enabled = true;
+	spin_unlock_bh(&hard_iface->bat_v.aggr_list.lock);
+
 	enable_delayed_work(&hard_iface->bat_v.aggr_wq);
 
 	batadv_v_ogm_start_queue_timer(hard_iface);
@@ -432,6 +443,7 @@ void batadv_v_ogm_iface_disable(struct batadv_hard_iface *hard_iface)
 	disable_delayed_work_sync(&hard_iface->bat_v.aggr_wq);
 
 	spin_lock_bh(&hard_iface->bat_v.aggr_list.lock);
+	hard_iface->bat_v.aggr_list_enabled = false;
 	batadv_v_ogm_aggr_list_free(hard_iface);
 	spin_unlock_bh(&hard_iface->bat_v.aggr_list.lock);
 }
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 5fd5bd358a249..5e81c93b8217d 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -145,6 +145,12 @@ struct batadv_hard_iface_bat_v {
 	/** @aggr_list: queue for to be aggregated OGM packets */
 	struct sk_buff_head aggr_list;
 
+	/**
+	 * @aggr_list_enabled: aggr_list is active and new skbs can be
+	 * enqueued. Protected by aggr_list.lock after initialization
+	 */
+	bool aggr_list_enabled:1;
+
 	/** @aggr_len: size of the OGM aggregate (excluding ethernet header) */
 	unsigned int aggr_len;
 
-- 
2.47.3