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 D90C4C4332F for ; Tue, 4 Jan 2022 03:00:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232470AbiADDAA (ORCPT ); Mon, 3 Jan 2022 22:00:00 -0500 Received: from out30-56.freemail.mail.aliyun.com ([115.124.30.56]:59861 "EHLO out30-56.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232440AbiADC77 (ORCPT ); Mon, 3 Jan 2022 21:59:59 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;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=8;SR=0;TI=SMTPD_---0V0oYYYM_1641265187; Received: from e02h04404.eu6sqa(mailfrom:guwen@linux.alibaba.com fp:SMTPD_---0V0oYYYM_1641265187) by smtp.aliyun-inc.com(127.0.0.1); Tue, 04 Jan 2022 10:59:57 +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, dust.li@linux.alibaba.com, tonylu@linux.alibaba.com Subject: [PATCH net v2] net/smc: Reset conn->lgr when link group registration fails Date: Tue, 4 Jan 2022 10:59:47 +0800 Message-Id: <1641265187-108970-1-git-send-email-guwen@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 occurs in smc_lgr_register_conn(), thus avoiding the crash caused by accessing the uninitialized resources in smc_conn_free(), and scheduling the link group's free work if it is new created. Fixes: 56bc3b2094b4 ("net/smc: assign link to a new connection") Signed-off-by: Wen Gu --- net/smc/smc_core.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index 412bc85..8edc43a 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -171,8 +171,10 @@ static int smc_lgr_register_conn(struct smc_connection *conn, bool first) if (!conn->lgr->is_smcd) { rc = smcr_lgr_conn_assign_link(conn, first); - if (rc) + if (rc) { + conn->lgr = NULL; return rc; + } } /* find a new alert_token_local value not yet used by some connection * in this link group @@ -1835,8 +1837,10 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini) write_lock_bh(&lgr->conns_lock); rc = smc_lgr_register_conn(conn, true); write_unlock_bh(&lgr->conns_lock); - if (rc) + if (rc) { + smc_lgr_schedule_free_work(lgr); goto out; + } } conn->local_tx_ctrl.common.type = SMC_CDC_MSG_TYPE; conn->local_tx_ctrl.len = SMC_WR_TX_SIZE; -- 1.8.3.1