From patchwork Sat Mar 5 14:53:47 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sven Eckelmann X-Patchwork-Id: 15888 X-Patchwork-Delegate: mareklindner@neomailbox.ch Return-Path: X-Original-To: patchwork@open-mesh.org Delivered-To: patchwork@open-mesh.org Received: from open-mesh.org (localhost [127.0.0.1]) by open-mesh.org (Postfix) with ESMTP id 42BBD82391; Sat, 5 Mar 2016 15:53:54 +0100 (CET) Authentication-Results: open-mesh.org; dkim=fail reason="verification failed; unprotected key" header.d=narfation.org header.i=@narfation.org header.b=W0/VSh6Z; dkim-adsp=fail (unprotected policy); dkim-atps=neutral Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=79.140.41.39; helo=v3-1039.vlinux.de; envelope-from=sven@narfation.org; receiver=b.a.t.m.a.n@lists.open-mesh.org Authentication-Results: open-mesh.org; dmarc=pass header.from=narfation.org Received: from v3-1039.vlinux.de (narfation.org [79.140.41.39]) by open-mesh.org (Postfix) with ESMTPS id 1A82982390 for ; Sat, 5 Mar 2016 15:53:51 +0100 (CET) Received: from sven-desktop.home.narfation.org (p200300C593C286FD0000000000002E16.dip0.t-ipconnect.de [IPv6:2003:c5:93c2:86fd::2e16]) by v3-1039.vlinux.de (Postfix) with ESMTPSA id 8A33C110103; Sat, 5 Mar 2016 15:53:51 +0100 (CET) Authentication-Results: v3-1039.vlinux.de; dmarc=none header.from=narfation.org DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=narfation.org; s=20121; t=1457189631; bh=OixwhWSZpNAXDFOzqJYUOLfKScTaxl3rKaEBl5y1kEk=; h=From:To:Cc:Subject:Date:From; b=W0/VSh6ZtjSBV4wn+c/GlrxEZbNVe26J7RyJ3668v3wp23QTfilAomAxDyanOGyZO r2ZnjTIHIaf1auv+bybB1Pu8Ayig8lGIvXUb61BT9Ss944sQqfnKJW7aoVOyFeutpb tUpkBGtS3bNEYyiqnuNEA5SLUjRs86tLkb+sYDA8= From: Sven Eckelmann To: b.a.t.m.a.n@lists.open-mesh.org Date: Sat, 5 Mar 2016 15:53:47 +0100 Message-Id: <1457189627-8839-1-git-send-email-sven@narfation.org> X-Mailer: git-send-email 2.7.0 Subject: [B.A.T.M.A.N.] [PATCH maint] batman-adv: Reduce refcnt of removed router when updating route 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" _batadv_update_route rcu_derefences orig_ifinfo->router outside of a spinlock protected region to print some information messages to the debug log. But this pointer is not checked again when the new pointer is assigned in the spinlock protected region. Thus is can happen that the value of orig_ifinfo->router changed in the meantime and thus the reference counter of the wrong router gets reduced after the spinlock protected region. Just rcu_dereferencing the value of orig_ifinfo->router inside the spinlock protected region (which also set the new pointer) is enough to get the correct old router object. Fixes: d90ddb94423f ("batman-adv: Make orig_node->router an rcu protected pointer") Signed-off-by: Sven Eckelmann --- net/batman-adv/routing.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c index 1fb1be3..61fdefe 100644 --- a/net/batman-adv/routing.c +++ b/net/batman-adv/routing.c @@ -104,6 +104,8 @@ static void _batadv_update_route(struct batadv_priv *bat_priv, neigh_node = NULL; spin_lock_bh(&orig_node->neigh_list_lock); + curr_router = rcu_dereference_protected(orig_ifinfo->router, true); + rcu_assign_pointer(orig_ifinfo->router, neigh_node); spin_unlock_bh(&orig_node->neigh_list_lock); batadv_orig_ifinfo_free_ref(orig_ifinfo);