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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 1AD90C43387 for ; Mon, 17 Dec 2018 14:59:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DDA2120874 for ; Mon, 17 Dec 2018 14:59:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387557AbeLQO7G (ORCPT ); Mon, 17 Dec 2018 09:59:06 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41632 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387545AbeLQO7F (ORCPT ); Mon, 17 Dec 2018 09:59:05 -0500 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id wBHEwtGe046857 for ; Mon, 17 Dec 2018 09:59:03 -0500 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2peaw5rrsc-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 17 Dec 2018 09:59:03 -0500 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 17 Dec 2018 14:59:02 -0000 Received: from b06cxnps4074.portsmouth.uk.ibm.com (9.149.109.196) by e06smtp02.uk.ibm.com (192.168.101.132) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 17 Dec 2018 14:58:59 -0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id wBHEwwJm62587016 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 17 Dec 2018 14:58:58 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B758811C05C; Mon, 17 Dec 2018 14:58:58 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7E0F811C054; Mon, 17 Dec 2018 14:58:58 +0000 (GMT) Received: from oc5311105230.ibm.com (unknown [9.145.57.218]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 17 Dec 2018 14:58:58 +0000 (GMT) Subject: Re: [PATCH v2] net/smc: fix TCP fallback socket release To: Myungho Jung Cc: "David S. Miller" , linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20181217052122.GA26299@myunghoj-Precision-5530> From: Ursula Braun Openpgp: preference=signencrypt Date: Mon, 17 Dec 2018 15:58:58 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181217052122.GA26299@myunghoj-Precision-5530> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18121714-0008-0000-0000-000002A29549 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18121714-0009-0000-0000-0000220D24DD Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-12-17_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1812170133 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/17/2018 06:21 AM, Myungho Jung wrote: > clcsock can be released while kernel_accept() references it in TCP > listen worker. Also, clcsock needs to wake up before released if TCP > fallback is used and the clcsock is blocked by accept. Add a lock to > safely release clcsock and call kernel_sock_shutdown() to wake up > clcsock from accept in smc_release(). Thanks for your effort to solve this problem. I have some minor improvement proposals: > > Reported-by: syzbot+0bf2e01269f1274b4b03@syzkaller.appspotmail.com > Reported-by: syzbot+e3132895630f957306bc@syzkaller.appspotmail.com > Signed-off-by: Myungho Jung > --- > net/smc/af_smc.c | 14 ++++++++++++-- > net/smc/smc.h | 2 ++ > 2 files changed, 14 insertions(+), 2 deletions(-) > > diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c > index 5fbaf1901571..5d06fb1bbccf 100644 > --- a/net/smc/af_smc.c > +++ b/net/smc/af_smc.c > @@ -147,8 +147,14 @@ static int smc_release(struct socket *sock) > sk->sk_shutdown |= SHUTDOWN_MASK; > } > if (smc->clcsock) { > + if (smc->use_fallback && sk->sk_state == SMC_LISTEN) { > + /* wake up clcsock accept */ > + rc = kernel_sock_shutdown(smc->clcsock, SHUT_RDWR); > + } This part is not needed, since an SMC socket in state SMC_LISTEN is never a use_fallback socket. > + mutex_lock(&smc->clcsock_release_lock); > sock_release(smc->clcsock); > smc->clcsock = NULL; > + mutex_unlock(&smc->clcsock_release_lock); > } > if (smc->use_fallback) { > if (sk->sk_state != SMC_LISTEN && sk->sk_state != SMC_INIT) > @@ -205,6 +211,7 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock, > spin_lock_init(&smc->conn.send_lock); > sk->sk_prot->hash(sk); > sk_refcnt_debug_inc(sk); > + mutex_init(&smc->clcsock_release_lock); > > return sk; > } > @@ -821,7 +828,7 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc) > struct socket *new_clcsock = NULL; > struct sock *lsk = &lsmc->sk; > struct sock *new_sk; > - int rc; > + int rc = 0; Without clcsock the good path should not be executed. Thus I suggest to initialize with something negative like -EINVAL. > > release_sock(lsk); > new_sk = smc_sock_alloc(sock_net(lsk), NULL, lsk->sk_protocol); > @@ -834,7 +841,10 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc) > } > *new_smc = smc_sk(new_sk); > > - rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0); > + mutex_lock(&lsmc->clcsock_release_lock); > + if (lsmc->clcsock) > + rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0); > + mutex_unlock(&lsmc->clcsock_release_lock); > lock_sock(lsk); > if (rc < 0) > lsk->sk_err = -rc; > diff --git a/net/smc/smc.h b/net/smc/smc.h > index 08786ace6010..9a2795cf5d30 100644 > --- a/net/smc/smc.h > +++ b/net/smc/smc.h > @@ -219,6 +219,8 @@ struct smc_sock { /* smc sock container */ > * started, waiting for unsent > * data to be sent > */ > + struct mutex clcsock_release_lock; > + /* protects clcsock */ I suggest to be more precise: "protects clcsock of a listen socket" > }; > > static inline struct smc_sock *smc_sk(const struct sock *sk) >