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=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 D0AF5C433DB for ; Thu, 11 Mar 2021 14:13:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D73464FA8 for ; Thu, 11 Mar 2021 14:13:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233376AbhCKONN (ORCPT ); Thu, 11 Mar 2021 09:13:13 -0500 Received: from mail.kernel.org ([198.145.29.99]:52186 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233256AbhCKOMx (ORCPT ); Thu, 11 Mar 2021 09:12:53 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 053A964E77; Thu, 11 Mar 2021 14:12:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615471972; bh=sdeipfns5kt1PWF6q1N5om3MHUtfAAJhqn4SCS/EBPk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Soj1WKpkFhwK59JYb09zMLDUjL4HNxWQnIixL9G7ymKCUNrRlUE01cyRbv6DQQfXF WWcaPV9cJCHldVZihN7oZsWNqHAMlWYaMsEUYZDZqEBrs372hZjstrqqG1iW/ssd/o XSt2F6irghQCO/9fS/iSbRQH12Kvn2qHwzY9O8YdBn5vg6xqrRvz+VfOJKOkDaAKCf YGRScjPPsXZ8YC97CTWR5sbGj0fzPx8K7pS9PvTcnoaDgpjUb2OiqKY5WdSyKcmdn+ ACmNmFOrsiG2Mw9iNzxHSjy41DFMbYEwRlAMKJVtqmUk/AGYVD29UFhRyrVVVToNfz ktTXXYS9RIZVw== Date: Thu, 11 Mar 2021 16:12:48 +0200 From: Leon Romanovsky To: lyl2019@mail.ustc.edu.cn Cc: dledford@redhat.com, jgg@ziepe.ca, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Re: Re: [PATCH] infiniband/core: Fix a use after free in cm_work_handler Message-ID: References: <20210311022153.3757-1-lyl2019@mail.ustc.edu.cn> <1149b747.c620.17820d56572.Coremail.lyl2019@mail.ustc.edu.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Thu, Mar 11, 2021 at 08:03:23PM +0800, lyl2019@mail.ustc.edu.cn wrote: > > > > > -----原始邮件----- > > 发件人: "Leon Romanovsky" > > 发送时间: 2021-03-11 19:05:03 (星期四) > > 收件人: lyl2019@mail.ustc.edu.cn > > 抄送: dledford@redhat.com, jgg@ziepe.ca, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org > > 主题: Re: Re: [PATCH] infiniband/core: Fix a use after free in cm_work_handler > > > > On Thu, Mar 11, 2021 at 06:29:19PM +0800, lyl2019@mail.ustc.edu.cn wrote: > > > In the implementation of destory_cm_id(), it restores cm_id_priv by > > > "cm_id_priv = container_of(cm_id, struct iwcm_id_private, id);". > > > > > > And the last line of destory_cm_id() calls "(void)iwcm_deref_id(cm_id_priv);" > > > to free the cm_id_priv. > > > > It is not enough to see double call to iwcm_deref_id() because it is > > protected with refcount to claim use-after-free. Did you hit the BUG_ON() > > for the second call to iwcm_deref_id()? > > > > And please don't do top-posting. > > > > Thanks > > > > > > > > > > > > -----原始邮件----- > > > > 发件人: "Leon Romanovsky" > > > > 发送时间: 2021-03-11 17:22:03 (星期四) > > > > 收件人: "Lv Yunlong" > > > > 抄送: dledford@redhat.com, jgg@ziepe.ca, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org > > > > 主题: Re: [PATCH] infiniband/core: Fix a use after free in cm_work_handler > > > > > > > > On Wed, Mar 10, 2021 at 06:21:53PM -0800, Lv Yunlong wrote: > > > > > In cm_work_handler, it calls destory_cm_id() to release > > > > > the initial reference of cm_id_priv taken by iw_create_cm_id() > > > > > and free the cm_id_priv. After destory_cm_id(), iwcm_deref_id > > > > > (cm_id_priv) will be called and cause a use after free. > > > > > > > > > > Fixes: 59c68ac31e15a ("iw_cm: free cm_id resources on the last deref") > > > > > Signed-off-by: Lv Yunlong > > > > > --- > > > > > drivers/infiniband/core/iwcm.c | 4 +++- > > > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > > > > > diff --git a/drivers/infiniband/core/iwcm.c b/drivers/infiniband/core/iwcm.c > > > > > index da8adadf4755..cb6b4ac45e21 100644 > > > > > --- a/drivers/infiniband/core/iwcm.c > > > > > +++ b/drivers/infiniband/core/iwcm.c > > > > > @@ -1035,8 +1035,10 @@ static void cm_work_handler(struct work_struct *_work) > > > > > > > > > > if (!test_bit(IWCM_F_DROP_EVENTS, &cm_id_priv->flags)) { > > > > > ret = process_event(cm_id_priv, &levent); > > > > > - if (ret) > > > > > + if (ret) { > > > > > destroy_cm_id(&cm_id_priv->id); > > > > > + return; > > > > > > > > The destroy_cm_id() is called to free ->id and not cm_id_priv. This "return" > > > > leaks cm_id_priv now and what "a use after free" do you see? > > > > > > > > > + } > > > > > } else > > > > > pr_debug("dropping event %d\n", levent.event); > > > > > if (iwcm_deref_id(cm_id_priv)) > > > > > -- > > > > > 2.25.1 > > > > > > > > > > > > I'm not familiar with debug the kernel, sorry.This problem was > reported by my code analyzer and reviewed by myself. > > But i think as long as destroy_cm_id() is called, iwcm_deref_id() will be called twice. > Then "BUG_ON(atomic_read(&cm_id_priv->refcount)==0);" in iwcm_deref_id() will be triggered. > > Is it not a true problem? I don't know, this is I'm trying to understand here. Thanks