From patchwork Sat Apr 30 17:06:03 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Antonio Quartulli X-Patchwork-Id: 16017 Return-Path: X-Original-To: patchwork@open-mesh.org Delivered-To: patchwork@open-mesh.org Received: from open-mesh.org (localhost [IPv6:::1]) by open-mesh.org (Postfix) with ESMTP id 3753C824B2; Sat, 30 Apr 2016 19:07:21 +0200 (CEST) Authentication-Results: open-mesh.org; dmarc=none header.from=unstable.cc Received-SPF: Permerror (SPF Permanent Error: Two or more type TXT spf records found.) identity=mailfrom; client-ip=5.148.176.60; helo=s2.neomailbox.net; envelope-from=a@unstable.cc; receiver=b.a.t.m.a.n@lists.open-mesh.org Authentication-Results: open-mesh.org; dmarc=none header.from=unstable.cc Received: from s2.neomailbox.net (s2.neomailbox.net [5.148.176.60]) by open-mesh.org (Postfix) with ESMTPS id 51A43809C7 for ; Sat, 30 Apr 2016 19:06:41 +0200 (CEST) From: Antonio Quartulli To: davem@davemloft.net Date: Sun, 1 May 2016 01:06:03 +0800 Message-Id: <1462035963-28970-5-git-send-email-a@unstable.cc> In-Reply-To: <1462035963-28970-1-git-send-email-a@unstable.cc> References: <1462035963-28970-1-git-send-email-a@unstable.cc> Cc: netdev@vger.kernel.org, b.a.t.m.a.n@lists.open-mesh.org, Antonio Quartulli , Marek Lindner Subject: [B.A.T.M.A.N.] [PATCH 4/4] batman-adv: Fix reference counting of hardif_neigh_node object for neigh_node X-BeenThere: b.a.t.m.a.n@lists.open-mesh.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: The list for a Better Approach To Mobile Ad-hoc Networking List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking Errors-To: b.a.t.m.a.n-bounces@lists.open-mesh.org Sender: "B.A.T.M.A.N" From: Sven Eckelmann The batadv_neigh_node was specific to a batadv_hardif_neigh_node and held an implicit reference to it. But this reference was never stored in form of a pointer in the batadv_neigh_node itself. Instead batadv_neigh_node_release depends on a consistent state of hard_iface->neigh_list and that batadv_hardif_neigh_get always returns the batadv_hardif_neigh_node object which it has a reference for. But batadv_hardif_neigh_get cannot guarantee that because it is working only with rcu_read_lock on this list. It can therefore happen that a neigh_addr is in this list twice or that batadv_hardif_neigh_get cannot find the batadv_hardif_neigh_node for an neigh_addr due to some other list operations taking place at the same time. Instead add a batadv_hardif_neigh_node pointer directly in batadv_neigh_node which will be used for the reference counter decremented on release of batadv_neigh_node. Fixes: cef63419f7db ("batman-adv: add list of unique single hop neighbors per hard-interface") Signed-off-by: Sven Eckelmann Signed-off-by: Marek Lindner Signed-off-by: Antonio Quartulli --- net/batman-adv/originator.c | 16 +++++----------- net/batman-adv/types.h | 2 ++ 2 files changed, 7 insertions(+), 11 deletions(-) diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c index d52f67a0c057..c355a824713c 100644 --- a/net/batman-adv/originator.c +++ b/net/batman-adv/originator.c @@ -250,7 +250,6 @@ static void batadv_neigh_node_release(struct kref *ref) { struct hlist_node *node_tmp; struct batadv_neigh_node *neigh_node; - struct batadv_hardif_neigh_node *hardif_neigh; struct batadv_neigh_ifinfo *neigh_ifinfo; struct batadv_algo_ops *bao; @@ -262,13 +261,7 @@ static void batadv_neigh_node_release(struct kref *ref) batadv_neigh_ifinfo_put(neigh_ifinfo); } - hardif_neigh = batadv_hardif_neigh_get(neigh_node->if_incoming, - neigh_node->addr); - if (hardif_neigh) { - /* batadv_hardif_neigh_get() increases refcount too */ - batadv_hardif_neigh_put(hardif_neigh); - batadv_hardif_neigh_put(hardif_neigh); - } + batadv_hardif_neigh_put(neigh_node->hardif_neigh); if (bao->bat_neigh_free) bao->bat_neigh_free(neigh_node); @@ -665,6 +658,10 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node, neigh_node->orig_node = orig_node; neigh_node->last_seen = jiffies; + /* increment unique neighbor refcount */ + kref_get(&hardif_neigh->refcount); + neigh_node->hardif_neigh = hardif_neigh; + /* extra reference for return */ kref_init(&neigh_node->refcount); kref_get(&neigh_node->refcount); @@ -673,9 +670,6 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node, hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list); spin_unlock_bh(&orig_node->neigh_list_lock); - /* increment unique neighbor refcount */ - kref_get(&hardif_neigh->refcount); - batadv_dbg(BATADV_DBG_BATMAN, orig_node->bat_priv, "Creating new neighbor %pM for orig_node %pM on interface %s\n", neigh_addr, orig_node->orig, hard_iface->net_dev->name); diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 65afd090ab3e..1e47fbe8bb7b 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -433,6 +433,7 @@ struct batadv_hardif_neigh_node { * @ifinfo_lock: lock protecting private ifinfo members and list * @if_incoming: pointer to incoming hard-interface * @last_seen: when last packet via this neighbor was received + * @hardif_neigh: hardif_neigh of this neighbor * @refcount: number of contexts the object is used * @rcu: struct used for freeing in an RCU-safe manner */ @@ -444,6 +445,7 @@ struct batadv_neigh_node { spinlock_t ifinfo_lock; /* protects ifinfo_list and its members */ struct batadv_hard_iface *if_incoming; unsigned long last_seen; + struct batadv_hardif_neigh_node *hardif_neigh; struct kref refcount; struct rcu_head rcu; };