From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E5822C4332E for ; Thu, 19 Mar 2020 13:37:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B4C7520663 for ; Thu, 19 Mar 2020 13:37:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584625077; bh=CXO2uhnFYDXcQ/2+gZnXq7HDfKx4gTcFAJjOcphPXME=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Bz0pV3i5XxhnB3rnA3DPxRdm2hnIzJqYh9TtXUgiiKlwiRK3SwBCSNL9kD9sQsJ/n ZZV1NX1QS8uA5PIsEpT+qckqEUABqAd7AZrgvynjLG7MkXC0R0pRDmmGHLRdesIrPn W1ABNuRzPkytxvtU7RzqhtmHDmA3NsFuyVT8UECk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727941AbgCSNHc (ORCPT ); Thu, 19 Mar 2020 09:07:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:51234 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727283AbgCSNHb (ORCPT ); Thu, 19 Mar 2020 09:07:31 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 284FD20788; Thu, 19 Mar 2020 13:07:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584623250; bh=CXO2uhnFYDXcQ/2+gZnXq7HDfKx4gTcFAJjOcphPXME=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=osOjVdH0CuNZrNMDTId3vcF807V287GTPPS1WO7gGd07dxWU3El1jAB7Q2q0U/ub2 zHmR8S8WkDPyqy7/12Koeu5ahY07GOpm3ihDSazB4tIp8r0mrX8ibYMQXImISzYMz7 Et8mFaewxLhCrrp4H+AXstWKvudTHM7IElbG7PIw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Sven Eckelmann , Marek Lindner , Antonio Quartulli Subject: [PATCH 4.4 39/93] batman-adv: Only put gw_node list reference when removed Date: Thu, 19 Mar 2020 13:59:43 +0100 Message-Id: <20200319123937.486678083@linuxfoundation.org> X-Mailer: git-send-email 2.25.2 In-Reply-To: <20200319123924.795019515@linuxfoundation.org> References: <20200319123924.795019515@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sven Eckelmann commit c18bdd018e8912ca73ad6c12120b7283b5038875 upstream. The batadv_gw_node reference counter in batadv_gw_node_update can only be reduced when the list entry was actually removed. Otherwise the reference counter may reach zero when batadv_gw_node_update is called from two different contexts for the same gw_node but only one context is actually removing the entry from the list. The release function for this gw_node is not called inside the list_lock spinlock protected region because the function batadv_gw_node_update still holds a gw_node reference for the object pointer on the stack. Thus the actual release function (when required) will be called only at the end of the function. Fixes: bd3524c14bd0 ("batman-adv: remove obsolete deleted attribute for gateway node") Signed-off-by: Sven Eckelmann Signed-off-by: Marek Lindner Signed-off-by: Antonio Quartulli Signed-off-by: Greg Kroah-Hartman --- net/batman-adv/gateway_client.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/net/batman-adv/gateway_client.c +++ b/net/batman-adv/gateway_client.c @@ -527,11 +527,12 @@ void batadv_gw_node_update(struct batadv * gets dereferenced. */ spin_lock_bh(&bat_priv->gw.list_lock); - hlist_del_init_rcu(&gw_node->list); + if (!hlist_unhashed(&gw_node->list)) { + hlist_del_init_rcu(&gw_node->list); + batadv_gw_node_free_ref(gw_node); + } spin_unlock_bh(&bat_priv->gw.list_lock); - batadv_gw_node_free_ref(gw_node); - curr_gw = batadv_gw_get_selected_gw_node(bat_priv); if (gw_node == curr_gw) batadv_gw_reselect(bat_priv);