[linux-next] LinuxNextTracking branch, master, updated. next-20180921

batman at open-mesh.org batman at open-mesh.org
Sat Sep 22 00:20:38 CEST 2018


The following commit has been merged in the master branch:
commit ae3cdc97dc10c7a3b31f297dab429bfb774c9ccb
Author: Sven Eckelmann <sven at narfation.org>
Date:   Sun Aug 12 21:04:45 2018 +0200

    batman-adv: Prevent duplicated tvlv handler
    
    The function batadv_tvlv_handler_register is responsible for adding new
    tvlv_handler to the handler_list. It first checks whether the entry
    already is in the list or not. If it is, then the creation of a new entry
    is aborted.
    
    But the lock for the list is only held when the list is really modified.
    This could lead to duplicated entries because another context could create
    an entry with the same key between the check and the list manipulation.
    
    The check and the manipulation of the list must therefore be in the same
    locked code section.
    
    Fixes: ef26157747d4 ("batman-adv: tvlv - basic infrastructure")
    Signed-off-by: Sven Eckelmann <sven at narfation.org>
    Signed-off-by: Simon Wunderlich <sw at simonwunderlich.de>

diff --git a/net/batman-adv/tvlv.c b/net/batman-adv/tvlv.c
index a637458205d1..40e69c9346d2 100644
--- a/net/batman-adv/tvlv.c
+++ b/net/batman-adv/tvlv.c
@@ -529,15 +529,20 @@ void batadv_tvlv_handler_register(struct batadv_priv *bat_priv,
 {
 	struct batadv_tvlv_handler *tvlv_handler;
 
+	spin_lock_bh(&bat_priv->tvlv.handler_list_lock);
+
 	tvlv_handler = batadv_tvlv_handler_get(bat_priv, type, version);
 	if (tvlv_handler) {
+		spin_unlock_bh(&bat_priv->tvlv.handler_list_lock);
 		batadv_tvlv_handler_put(tvlv_handler);
 		return;
 	}
 
 	tvlv_handler = kzalloc(sizeof(*tvlv_handler), GFP_ATOMIC);
-	if (!tvlv_handler)
+	if (!tvlv_handler) {
+		spin_unlock_bh(&bat_priv->tvlv.handler_list_lock);
 		return;
+	}
 
 	tvlv_handler->ogm_handler = optr;
 	tvlv_handler->unicast_handler = uptr;
@@ -547,7 +552,6 @@ void batadv_tvlv_handler_register(struct batadv_priv *bat_priv,
 	kref_init(&tvlv_handler->refcount);
 	INIT_HLIST_NODE(&tvlv_handler->list);
 
-	spin_lock_bh(&bat_priv->tvlv.handler_list_lock);
 	kref_get(&tvlv_handler->refcount);
 	hlist_add_head_rcu(&tvlv_handler->list, &bat_priv->tvlv.handler_list);
 	spin_unlock_bh(&bat_priv->tvlv.handler_list_lock);

-- 
LinuxNextTracking


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