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=ham 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 02E64C4332D for ; Thu, 19 Mar 2020 13:17:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C66DA20787 for ; Thu, 19 Mar 2020 13:17:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584623868; bh=mMm4aKNCivrgGGkrQe0BBkRKYheBNjuptlaDsXjg8Lg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=WHoVka9dXCoS2SN6bGQ7wLOmmHpW0NPTZ3JUnQ9YNSQnWDJfr7CKfx2OLlnIcQ3x0 PDI2WQ3TuzixJjkYUtDXAac0FTEC+Pnjdk7/tgqkPZZP7vSxeKah1J1quaoP/3IqsD CU+Bu2VpNf98dJMBZXZPSKVoGuwR6MWMbEnuj+b4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729707AbgCSNRr (ORCPT ); Thu, 19 Mar 2020 09:17:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:39218 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729315AbgCSNRp (ORCPT ); Thu, 19 Mar 2020 09:17:45 -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 C8F3B20724; Thu, 19 Mar 2020 13:17:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584623864; bh=mMm4aKNCivrgGGkrQe0BBkRKYheBNjuptlaDsXjg8Lg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dw0ObVFVyjrgzs+WrAtOS9aNjM3y47csqzaAjhDhGmFA00pIgdYp3qnVkoJyyLUB6 mB4bm/mQ/AcMX+Y2LUreOzbAlcMNxL8k7fIhgg03SgEh4S1riGn4LwCblg74RsT/z3 qvaxSnyF/5KoxjRDMh+gfmaZtnMc3CeJVBt2Zxzo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , syzbot+0cc629f19ccb8534935b@syzkaller.appspotmail.com, Sven Eckelmann , Simon Wunderlich Subject: [PATCH 4.14 80/99] batman-adv: Avoid free/alloc race when handling OGM buffer Date: Thu, 19 Mar 2020 14:03:58 +0100 Message-Id: <20200319124004.841054033@linuxfoundation.org> X-Mailer: git-send-email 2.25.2 In-Reply-To: <20200319123941.630731708@linuxfoundation.org> References: <20200319123941.630731708@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sven Eckelmann commit 40e220b4218bb3d278e5e8cc04ccdfd1c7ff8307 upstream. Each slave interface of an B.A.T.M.A.N. IV virtual interface has an OGM packet buffer which is initialized using data from netdevice notifier and other rtnetlink related hooks. It is sent regularly via various slave interfaces of the batadv virtual interface and in this process also modified (realloced) to integrate additional state information via TVLV containers. It must be avoided that the worker item is executed without a common lock with the netdevice notifier/rtnetlink helpers. Otherwise it can either happen that half modified/freed data is sent out or functions modifying the OGM buffer try to access already freed memory regions. Reported-by: syzbot+0cc629f19ccb8534935b@syzkaller.appspotmail.com Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol") Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich Signed-off-by: Greg Kroah-Hartman --- net/batman-adv/bat_iv_ogm.c | 60 ++++++++++++++++++++++++++++++++++------ net/batman-adv/hard-interface.c | 2 + net/batman-adv/types.h | 2 + 3 files changed, 55 insertions(+), 9 deletions(-) --- a/net/batman-adv/bat_iv_ogm.c +++ b/net/batman-adv/bat_iv_ogm.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #include #include @@ -370,14 +371,18 @@ static int batadv_iv_ogm_iface_enable(st unsigned char *ogm_buff; u32 random_seqno; + mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex); + /* randomize initial seqno to avoid collision */ get_random_bytes(&random_seqno, sizeof(random_seqno)); atomic_set(&hard_iface->bat_iv.ogm_seqno, random_seqno); hard_iface->bat_iv.ogm_buff_len = BATADV_OGM_HLEN; ogm_buff = kmalloc(hard_iface->bat_iv.ogm_buff_len, GFP_ATOMIC); - if (!ogm_buff) + if (!ogm_buff) { + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); return -ENOMEM; + } hard_iface->bat_iv.ogm_buff = ogm_buff; @@ -389,35 +394,59 @@ static int batadv_iv_ogm_iface_enable(st batadv_ogm_packet->reserved = 0; batadv_ogm_packet->tq = BATADV_TQ_MAX_VALUE; + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); + return 0; } static void batadv_iv_ogm_iface_disable(struct batadv_hard_iface *hard_iface) { + mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex); + kfree(hard_iface->bat_iv.ogm_buff); hard_iface->bat_iv.ogm_buff = NULL; + + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); } static void batadv_iv_ogm_iface_update_mac(struct batadv_hard_iface *hard_iface) { struct batadv_ogm_packet *batadv_ogm_packet; - unsigned char *ogm_buff = hard_iface->bat_iv.ogm_buff; + void *ogm_buff; - batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff; + mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex); + + ogm_buff = hard_iface->bat_iv.ogm_buff; + if (!ogm_buff) + goto unlock; + + batadv_ogm_packet = ogm_buff; ether_addr_copy(batadv_ogm_packet->orig, hard_iface->net_dev->dev_addr); ether_addr_copy(batadv_ogm_packet->prev_sender, hard_iface->net_dev->dev_addr); + +unlock: + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); } static void batadv_iv_ogm_primary_iface_set(struct batadv_hard_iface *hard_iface) { struct batadv_ogm_packet *batadv_ogm_packet; - unsigned char *ogm_buff = hard_iface->bat_iv.ogm_buff; + void *ogm_buff; - batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff; + mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex); + + ogm_buff = hard_iface->bat_iv.ogm_buff; + if (!ogm_buff) + goto unlock; + + batadv_ogm_packet = ogm_buff; batadv_ogm_packet->ttl = BATADV_TTL; + +unlock: + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); } /* when do we schedule our own ogm to be sent */ @@ -915,7 +944,11 @@ batadv_iv_ogm_slide_own_bcast_window(str } } -static void batadv_iv_ogm_schedule(struct batadv_hard_iface *hard_iface) +/** + * batadv_iv_ogm_schedule_buff() - schedule submission of hardif ogm buffer + * @hard_iface: interface whose ogm buffer should be transmitted + */ +static void batadv_iv_ogm_schedule_buff(struct batadv_hard_iface *hard_iface) { struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface); unsigned char **ogm_buff = &hard_iface->bat_iv.ogm_buff; @@ -926,9 +959,7 @@ static void batadv_iv_ogm_schedule(struc u16 tvlv_len = 0; unsigned long send_time; - if ((hard_iface->if_status == BATADV_IF_NOT_IN_USE) || - (hard_iface->if_status == BATADV_IF_TO_BE_REMOVED)) - return; + lockdep_assert_held(&hard_iface->bat_iv.ogm_buff_mutex); /* the interface gets activated here to avoid race conditions between * the moment of activating the interface in @@ -996,6 +1027,17 @@ out: batadv_hardif_put(primary_if); } +static void batadv_iv_ogm_schedule(struct batadv_hard_iface *hard_iface) +{ + if (hard_iface->if_status == BATADV_IF_NOT_IN_USE || + hard_iface->if_status == BATADV_IF_TO_BE_REMOVED) + return; + + mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex); + batadv_iv_ogm_schedule_buff(hard_iface); + mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex); +} + /** * batadv_iv_ogm_orig_update - use OGM to update corresponding data in an * originator --- a/net/batman-adv/hard-interface.c +++ b/net/batman-adv/hard-interface.c @@ -28,6 +28,7 @@ #include #include #include +#include #include #include #include @@ -901,6 +902,7 @@ batadv_hardif_add_interface(struct net_d INIT_LIST_HEAD(&hard_iface->list); INIT_HLIST_HEAD(&hard_iface->neigh_list); + mutex_init(&hard_iface->bat_iv.ogm_buff_mutex); spin_lock_init(&hard_iface->neigh_list_lock); kref_init(&hard_iface->refcount); --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -82,11 +82,13 @@ enum batadv_dhcp_recipient { * @ogm_buff: buffer holding the OGM packet * @ogm_buff_len: length of the OGM packet buffer * @ogm_seqno: OGM sequence number - used to identify each OGM + * @ogm_buff_mutex: lock protecting ogm_buff and ogm_buff_len */ struct batadv_hard_iface_bat_iv { unsigned char *ogm_buff; int ogm_buff_len; atomic_t ogm_seqno; + struct mutex ogm_buff_mutex; }; /**