From patchwork Tue Dec 28 07:49:30 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wen Gu X-Patchwork-Id: 12700225 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7DE3AC433EF for ; Tue, 28 Dec 2021 07:49:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235397AbhL1Htq (ORCPT ); Tue, 28 Dec 2021 02:49:46 -0500 Received: from out30-45.freemail.mail.aliyun.com ([115.124.30.45]:57203 "EHLO out30-45.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235393AbhL1Htq (ORCPT ); Tue, 28 Dec 2021 02:49:46 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=guwen@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0V04IY3i_1640677771; Received: from e02h04404.eu6sqa(mailfrom:guwen@linux.alibaba.com fp:SMTPD_---0V04IY3i_1640677771) by smtp.aliyun-inc.com(127.0.0.1); Tue, 28 Dec 2021 15:49:44 +0800 From: Wen Gu To: kgraul@linux.ibm.com, davem@davemloft.net, kuba@kernel.org Cc: linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH net] net/smc: Reset conn->lgr when link group registration fails Date: Tue, 28 Dec 2021 15:49:30 +0800 Message-Id: <1640677770-112053-1-git-send-email-guwen@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org X-Patchwork-State: RFC SMC connections might fail to be registered to a link group due to things like unable to find a link to assign to in its creation. As a result, connection creation will return a failure and most resources related to the connection won't be applied or initialized, such as conn->abort_work or conn->lnk. If smc_conn_free() is invoked later, it will try to access the resources related to the connection, which wasn't initialized, thus causing a panic. Here is an example, a SMC-R connection failed to be registered to a link group and conn->lnk is NULL. The following crash will happen if smc_conn_free() tries to access conn->lnk in smc_cdc_tx_dismiss_slots(). BUG: kernel NULL pointer dereference, address: 0000000000000168 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 4 PID: 68 Comm: kworker/4:1 Kdump: loaded Tainted: G E 5.16.0-rc5+ #52 Workqueue: smc_hs_wq smc_listen_work [smc] RIP: 0010:smc_wr_tx_dismiss_slots+0x1e/0xc0 [smc] Call Trace: smc_conn_free+0xd8/0x100 [smc] smc_lgr_cleanup_early+0x15/0x90 [smc] smc_listen_work+0x302/0x1230 [smc] ? process_one_work+0x25c/0x600 process_one_work+0x25c/0x600 worker_thread+0x4f/0x3a0 ? process_one_work+0x600/0x600 kthread+0x15d/0x1a0 ? set_kthread_struct+0x40/0x40 ret_from_fork+0x1f/0x30 This patch tries to fix this by resetting conn->lgr to NULL if an abnormal exit due to lgr register failure occurs in smc_conn_create(), thus avoiding the crash caused by accessing the uninitialized resources in smc_conn_free(). Signed-off-by: Wen Gu --- net/smc/smc_core.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index 412bc85..1f40b8e 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -1815,7 +1815,7 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini) } spin_unlock_bh(lgr_lock); if (rc) - return rc; + goto out_unreg; if (role == SMC_CLNT && !ini->first_contact_peer && ini->first_contact_local) { @@ -1836,7 +1836,7 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini) rc = smc_lgr_register_conn(conn, true); write_unlock_bh(&lgr->conns_lock); if (rc) - goto out; + goto out_unreg; } conn->local_tx_ctrl.common.type = SMC_CDC_MSG_TYPE; conn->local_tx_ctrl.len = SMC_WR_TX_SIZE; @@ -1855,6 +1855,12 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini) out: return rc; +out_unreg: + /* fail to register connection into a link group */ + if (!lgr->conns_num && !delayed_work_pending(&lgr->free_work)) + smc_lgr_schedule_free_work(lgr); + conn->lgr = NULL; + return rc; } #define SMCD_DMBE_SIZES 6 /* 0 -> 16KB, 1 -> 32KB, .. 6 -> 1MB */