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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS,URIBL_BLOCKED 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 43EC9C43387 for ; Sun, 23 Dec 2018 21:03:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0CD3A2184D for ; Sun, 23 Dec 2018 21:03:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725859AbeLWVDj (ORCPT ); Sun, 23 Dec 2018 16:03:39 -0500 Received: from relay.sw.ru ([185.231.240.75]:45198 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725856AbeLWVDj (ORCPT ); Sun, 23 Dec 2018 16:03:39 -0500 Received: from [172.16.24.21] by relay.sw.ru with esmtp (Exim 4.91) (envelope-from ) id 1gbAuF-0008Ki-Sb; Mon, 24 Dec 2018 00:03:27 +0300 Subject: Re: [PATCH 1/4] nfs: use-after-free in svc_process_common() To: "bfields@fieldses.org" Cc: Trond Myklebust , "anna.schumaker@netapp.com" , "khorenko@virtuozzo.com" , "linux-nfs@vger.kernel.org" , "eshatokhin@virtuozzo.com" , "chuck.lever@oracle.com" , "jlayton@kernel.org" References: <134cf19c-e698-abed-02de-1659f9a5d4fb@virtuozzo.com> <20181217215026.GA8564@fieldses.org> <67f477b704d34b369f0530891a219f383f964001.camel@hammerspace.com> <4d878140-02c0-e306-fee6-1573d9fdecf2@virtuozzo.com> <068f1741afc54367853a2e4501fd95c2ab12a989.camel@hammerspace.com> <20181221010007.GA10196@fieldses.org> <9082b04a-8235-4b9d-39ae-1462fe350935@virtuozzo.com> <20181223205252.GA2613@fieldses.org> From: Vasily Averin Message-ID: Date: Mon, 24 Dec 2018 00:03:25 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181223205252.GA2613@fieldses.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On 12/23/18 11:52 PM, bfields@fieldses.org wrote: > On Sat, Dec 22, 2018 at 08:46:55PM +0300, Vasily Averin wrote: >> On 12/21/18 4:00 AM, bfields@fieldses.org wrote: >>> On Tue, Dec 18, 2018 at 02:55:15PM +0000, Trond Myklebust wrote: >>>> No. We don't care about xpt_flags for the back channel because there is >>>> no "server transport". The actual transport is stored in the 'struct >>>> rpc_rqst', and is the struct rpc_xprt corresponding to the client >>>> socket or RDMA channel. >>>> >>>> IOW: All we really need in svc_process_common() is to be able to run >>>> rqstp->rq_xprt->xpt_ops->xpo_prep_reply_hdr(), and that can be passed >>>> either as a pointer to the struct svc_xprt_ops itself. >>> >>> For what it's worth, I'd rather get rid of that op--it's an awfully >>> roundabout way just to do "svc_putnl(resv, 0);" in the tcp case. >> >> Do you mean that svc_create_xprt(serv, "tcp-bc", ...) was used ONLY to call >> svc_tcp_prep_reply_hdr() in svc_process_common() ? >> And according call for rdma-bc does nothing useful at all? > > Right, in the rdma case it's: > > void svc_rdma_prep_reply_hdr(struct svc_rqst *rqstp) > { > } > >> I've just tried to remove svc_create_xprt() from xs_tcp_bc_up() and >> just provide pointer to svc_tcp_prep_reply_hdr() in >> svc_process_common() via per-netns sunrpc_net -- and seems it was >> enough, my testcase worked correctly. >> >> Am I missed something probably? Should we really remove >> svc_create_xprt( "tcp/rdma-bc"...) related stuff? ? > > Haven't looked carefully, but off the top of my head I can't see why > that wouldn't work. I've prepared new patch version removed svc_create_xprt( "tcp/rdma-bc"...) as far as I see it works correctly. I'm going to submit it tomorrow morning. > I also tried some patches that replace that op by a flag bit (doesn't > address the original problem here, just seemed like a simplification): > > git://linux-nfs.org/~bfields/linux-topics.git > > but I don't if that's compatible with what you've done. > > --b. >