From patchwork Wed Mar 18 03:48:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yue Haibing X-Patchwork-Id: 222337 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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, 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 03F79C5ACD6 for ; Wed, 18 Mar 2020 03:50:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC9F420738 for ; Wed, 18 Mar 2020 03:50:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726874AbgCRDuX (ORCPT ); Tue, 17 Mar 2020 23:50:23 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:11657 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726229AbgCRDuX (ORCPT ); Tue, 17 Mar 2020 23:50:23 -0400 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 0C22517E85C3098C7E5D; Wed, 18 Mar 2020 11:50:21 +0800 (CST) Received: from localhost (10.173.223.234) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.487.0; Wed, 18 Mar 2020 11:50:11 +0800 From: YueHaibing To: , , , , CC: , , YueHaibing Subject: [PATCH] xfrm: policy: Fix doulbe free in xfrm_policy_timer Date: Wed, 18 Mar 2020 11:48:39 +0800 Message-ID: <20200318034839.57996-1-yuehaibing@huawei.com> X-Mailer: git-send-email 2.10.2.windows.1 MIME-Version: 1.0 X-Originating-IP: [10.173.223.234] X-CFilter-Loop: Reflected Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 add write_lock_bh in xfrm_policy_kill. Fixes: ea2dea9dacc2 ("xfrm: remove policy lock when accessing policy->walk.dead") Signed-off-by: YueHaibing --- net/xfrm/xfrm_policy.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index dbda08ec566e..ae0689174bbf 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -434,6 +434,7 @@ EXPORT_SYMBOL(xfrm_policy_destroy); static void xfrm_policy_kill(struct xfrm_policy *policy) { + write_lock_bh(&policy->lock); policy->walk.dead = 1; atomic_inc(&policy->genid); @@ -445,6 +446,7 @@ static void xfrm_policy_kill(struct xfrm_policy *policy) if (del_timer(&policy->timer)) xfrm_pol_put(policy); + write_lock_bh(&policy->lock); xfrm_pol_put(policy); }