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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 B8AD6C1975A for ; Wed, 25 Mar 2020 12:54:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 958D72076A for ; Wed, 25 Mar 2020 12:54:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727510AbgCYMyB (ORCPT ); Wed, 25 Mar 2020 08:54:01 -0400 Received: from a.mx.secunet.com ([62.96.220.36]:35012 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727279AbgCYMyB (ORCPT ); Wed, 25 Mar 2020 08:54:01 -0400 Received: from localhost (localhost [127.0.0.1]) by a.mx.secunet.com (Postfix) with ESMTP id 8753520265; Wed, 25 Mar 2020 13:53:59 +0100 (CET) X-Virus-Scanned: by secunet Received: from a.mx.secunet.com ([127.0.0.1]) by localhost (a.mx.secunet.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Zrh3ebZnZWSs; Wed, 25 Mar 2020 13:53:57 +0100 (CET) Received: from mail-essen-01.secunet.de (mail-essen-01.secunet.de [10.53.40.204]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by a.mx.secunet.com (Postfix) with ESMTPS id 9A11A20539; Wed, 25 Mar 2020 13:53:57 +0100 (CET) Received: from mbx-essen-02.secunet.de (10.53.40.198) by MAIL-ESSEN-01.secunet.de (10.53.40.204) with Microsoft SMTP Server (TLS) id 14.3.487.0; Wed, 25 Mar 2020 13:53:57 +0100 Received: from gauss2.secunet.de (10.182.7.193) by mbx-essen-02.secunet.de (10.53.40.198) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Wed, 25 Mar 2020 13:53:57 +0100 Received: by gauss2.secunet.de (Postfix, from userid 1000) id C5FDD318026D; Wed, 25 Mar 2020 13:53:56 +0100 (CET) Date: Wed, 25 Mar 2020 13:53:56 +0100 From: Steffen Klassert To: YueHaibing CC: , , , , , Subject: Re: [PATCH v3] xfrm: policy: Fix doulbe free in xfrm_policy_timer Message-ID: <20200325125356.GV13121@gauss3.secunet.de> References: <20200318034839.57996-1-yuehaibing@huawei.com> <20200323073239.59000-1-yuehaibing@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20200323073239.59000-1-yuehaibing@huawei.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-ClientProxiedBy: cas-essen-02.secunet.de (10.53.40.202) To mbx-essen-02.secunet.de (10.53.40.198) X-EXCLAIMER-MD-CONFIG: 2c86f778-e09b-4440-8b15-867914633a10 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 23, 2020 at 03:32:39PM +0800, YueHaibing wrote: > After xfrm_add_policy add a policy, its ref is 2, then > > xfrm_policy_timer > read_lock > xp->walk.dead is 0 > .... > mod_timer() > xfrm_policy_kill > policy->walk.dead = 1 > .... > del_timer(&policy->timer) > xfrm_pol_put //ref is 1 > xfrm_pol_put //ref is 0 > xfrm_policy_destroy > call_rcu > xfrm_pol_hold //ref is 1 > read_unlock > xfrm_pol_put //ref is 0 > xfrm_policy_destroy > call_rcu > > xfrm_policy_destroy is called twice, which may leads to > double free. > > Call Trace: > RIP: 0010:refcount_warn_saturate+0x161/0x210 > ... > xfrm_policy_timer+0x522/0x600 > call_timer_fn+0x1b3/0x5e0 > ? __xfrm_decode_session+0x2990/0x2990 > ? msleep+0xb0/0xb0 > ? _raw_spin_unlock_irq+0x24/0x40 > ? __xfrm_decode_session+0x2990/0x2990 > ? __xfrm_decode_session+0x2990/0x2990 > run_timer_softirq+0x5c5/0x10e0 > > Fix this by use write_lock_bh in xfrm_policy_kill. > > Fixes: ea2dea9dacc2 ("xfrm: remove policy lock when accessing policy->walk.dead") > Signed-off-by: YueHaibing > --- > v3: Only lock 'policy->walk.dead' > v2: Fix typo 'write_lock_bh'--> 'write_unlock_bh' while unlocking > --- Applied, thanks everyone!