From patchwork Wed Sep 15 09:20:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12495811 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 16E13C433FE for ; Wed, 15 Sep 2021 09:10:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F179061246 for ; Wed, 15 Sep 2021 09:10:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237145AbhIOJLj (ORCPT ); Wed, 15 Sep 2021 05:11:39 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:19982 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237098AbhIOJLj (ORCPT ); Wed, 15 Sep 2021 05:11:39 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4H8Z844cWQzbmT7; Wed, 15 Sep 2021 17:06:12 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:18 +0800 Received: from huawei.com (10.175.127.227) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:18 +0800 From: Yu Kuai To: , , , CC: , , , , Subject: [PATCH v7 1/6] nbd: don't handle response without a corresponding request message Date: Wed, 15 Sep 2021 17:20:05 +0800 Message-ID: <20210915092010.2087371-2-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210915092010.2087371-1-yukuai3@huawei.com> References: <20210915092010.2087371-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org While handling a response message from server, nbd_read_stat() will try to get request by tag, and then complete the request. However, this is problematic if nbd haven't sent a corresponding request message: t1 t2 submit_bio nbd_queue_rq blk_mq_start_request recv_work nbd_read_stat blk_mq_tag_to_rq blk_mq_complete_request nbd_send_cmd Thus add a new cmd flag 'NBD_CMD_INFLIGHT', it will be set in nbd_send_cmd() and checked in nbd_read_stat(). Noted that this patch can't fix that blk_mq_tag_to_rq() might return a freed request, and this will be fixed in following patches. Signed-off-by: Yu Kuai Reviewed-by: Ming Lei --- drivers/block/nbd.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 5170a630778d..23ded569e8d3 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -126,6 +126,12 @@ struct nbd_device { }; #define NBD_CMD_REQUEUED 1 +/* + * This flag will be set if nbd_queue_rq() succeed, and will be checked and + * cleared in completion. Both setting and clearing of the flag are protected + * by cmd->lock. + */ +#define NBD_CMD_INFLIGHT 2 struct nbd_cmd { struct nbd_device *nbd; @@ -400,6 +406,7 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req, if (!mutex_trylock(&cmd->lock)) return BLK_EH_RESET_TIMER; + __clear_bit(NBD_CMD_INFLIGHT, &cmd->flags); if (!refcount_inc_not_zero(&nbd->config_refs)) { cmd->status = BLK_STS_TIMEOUT; mutex_unlock(&cmd->lock); @@ -729,6 +736,12 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index) cmd = blk_mq_rq_to_pdu(req); mutex_lock(&cmd->lock); + if (!__test_and_clear_bit(NBD_CMD_INFLIGHT, &cmd->flags)) { + dev_err(disk_to_dev(nbd->disk), "Suspicious reply %d (status %u flags %lu)", + tag, cmd->status, cmd->flags); + ret = -ENOENT; + goto out; + } if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) { dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n", req, cmd->cmd_cookie, nbd_handle_to_cookie(handle)); @@ -828,6 +841,7 @@ static bool nbd_clear_req(struct request *req, void *data, bool reserved) return true; mutex_lock(&cmd->lock); + __clear_bit(NBD_CMD_INFLIGHT, &cmd->flags); cmd->status = BLK_STS_IOERR; mutex_unlock(&cmd->lock); @@ -964,7 +978,13 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) * returns EAGAIN can be retried on a different socket. */ ret = nbd_send_cmd(nbd, cmd, index); - if (ret == -EAGAIN) { + /* + * Access to this flag is protected by cmd->lock, thus it's safe to set + * the flag after nbd_send_cmd() succeed to send request to server. + */ + if (!ret) + __set_bit(NBD_CMD_INFLIGHT, &cmd->flags); + else if (ret == -EAGAIN) { dev_err_ratelimited(disk_to_dev(nbd->disk), "Request send failed, requeueing\n"); nbd_mark_nsock_dead(nbd, nsock, 1); From patchwork Wed Sep 15 09:20:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12495813 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 BD53EC43219 for ; Wed, 15 Sep 2021 09:10:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A544061242 for ; Wed, 15 Sep 2021 09:10:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237138AbhIOJLk (ORCPT ); Wed, 15 Sep 2021 05:11:40 -0400 Received: from szxga08-in.huawei.com ([45.249.212.255]:16211 "EHLO szxga08-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237132AbhIOJLj (ORCPT ); Wed, 15 Sep 2021 05:11:39 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.54]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4H8ZCf5T63z1DGwW; Wed, 15 Sep 2021 17:09:18 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:19 +0800 Received: from huawei.com (10.175.127.227) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:18 +0800 From: Yu Kuai To: , , , CC: , , , , Subject: [PATCH v7 2/6] nbd: make sure request completion won't concurrent Date: Wed, 15 Sep 2021 17:20:06 +0800 Message-ID: <20210915092010.2087371-3-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210915092010.2087371-1-yukuai3@huawei.com> References: <20210915092010.2087371-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org commit cddce0116058 ("nbd: Aovid double completion of a request") try to fix that nbd_clear_que() and recv_work() can complete a request concurrently. However, the problem still exists: t1 t2 t3 nbd_disconnect_and_put flush_workqueue recv_work blk_mq_complete_request blk_mq_complete_request_remote -> this is true WRITE_ONCE(rq->state, MQ_RQ_COMPLETE) blk_mq_raise_softirq blk_done_softirq blk_complete_reqs nbd_complete_rq blk_mq_end_request blk_mq_free_request WRITE_ONCE(rq->state, MQ_RQ_IDLE) nbd_clear_que blk_mq_tagset_busy_iter nbd_clear_req __blk_mq_free_request blk_mq_put_tag blk_mq_complete_request -> complete again There are three places where request can be completed in nbd: recv_work(), nbd_clear_que() and nbd_xmit_timeout(). Since they all hold cmd->lock before completing the request, it's easy to avoid the problem by setting and checking a cmd flag. Signed-off-by: Yu Kuai Reviewed-by: Ming Lei --- drivers/block/nbd.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 23ded569e8d3..614c6ab2b8fe 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -406,7 +406,11 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req, if (!mutex_trylock(&cmd->lock)) return BLK_EH_RESET_TIMER; - __clear_bit(NBD_CMD_INFLIGHT, &cmd->flags); + if (!__test_and_clear_bit(NBD_CMD_INFLIGHT, &cmd->flags)) { + mutex_unlock(&cmd->lock); + return BLK_EH_DONE; + } + if (!refcount_inc_not_zero(&nbd->config_refs)) { cmd->status = BLK_STS_TIMEOUT; mutex_unlock(&cmd->lock); @@ -841,7 +845,10 @@ static bool nbd_clear_req(struct request *req, void *data, bool reserved) return true; mutex_lock(&cmd->lock); - __clear_bit(NBD_CMD_INFLIGHT, &cmd->flags); + if (!__test_and_clear_bit(NBD_CMD_INFLIGHT, &cmd->flags)) { + mutex_unlock(&cmd->lock); + return true; + } cmd->status = BLK_STS_IOERR; mutex_unlock(&cmd->lock); From patchwork Wed Sep 15 09:20:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12495821 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 AAA41C433FE for ; Wed, 15 Sep 2021 09:10:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 948DA61242 for ; Wed, 15 Sep 2021 09:10:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237348AbhIOJLw (ORCPT ); Wed, 15 Sep 2021 05:11:52 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:15420 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237228AbhIOJLp (ORCPT ); Wed, 15 Sep 2021 05:11:45 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4H8Z894VRRzRB7x; Wed, 15 Sep 2021 17:06:17 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:19 +0800 Received: from huawei.com (10.175.127.227) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:19 +0800 From: Yu Kuai To: , , , CC: , , , , Subject: [PATCH v7 3/6] nbd: check sock index in nbd_read_stat() Date: Wed, 15 Sep 2021 17:20:07 +0800 Message-ID: <20210915092010.2087371-4-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210915092010.2087371-1-yukuai3@huawei.com> References: <20210915092010.2087371-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org The sock that clent send request in nbd_send_cmd() and receive reply in nbd_read_stat() should be the same. Signed-off-by: Yu Kuai --- drivers/block/nbd.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 614c6ab2b8fe..c724a5bd7fa4 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -746,6 +746,10 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index) ret = -ENOENT; goto out; } + if (cmd->index != index) { + dev_err(disk_to_dev(nbd->disk), "Unexpected reply %d from different sock %d (expected %d)", + tag, index, cmd->index); + } if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) { dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n", req, cmd->cmd_cookie, nbd_handle_to_cookie(handle)); From patchwork Wed Sep 15 09:20:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12495815 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 BF9BAC433FE for ; Wed, 15 Sep 2021 09:10:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE0B461242 for ; Wed, 15 Sep 2021 09:10:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237190AbhIOJLl (ORCPT ); Wed, 15 Sep 2021 05:11:41 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:9049 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229785AbhIOJLk (ORCPT ); Wed, 15 Sep 2021 05:11:40 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4H8ZCg3stmzW2gX; Wed, 15 Sep 2021 17:09:19 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:20 +0800 Received: from huawei.com (10.175.127.227) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:19 +0800 From: Yu Kuai To: , , , CC: , , , , Subject: [PATCH v7 4/6] nbd: don't start request if nbd_queue_rq() failed Date: Wed, 15 Sep 2021 17:20:08 +0800 Message-ID: <20210915092010.2087371-5-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210915092010.2087371-1-yukuai3@huawei.com> References: <20210915092010.2087371-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Currently, blk_mq_end_request() will be called if nbd_queue_rq() failed, thus start request in such situation is useless. Signed-off-by: Yu Kuai Reviewed-by: Christoph Hellwig --- drivers/block/nbd.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index c724a5bd7fa4..22c91d8901f6 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -934,7 +934,6 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) if (!refcount_inc_not_zero(&nbd->config_refs)) { dev_err_ratelimited(disk_to_dev(nbd->disk), "Socks array is empty\n"); - blk_mq_start_request(req); return -EINVAL; } config = nbd->config; @@ -943,7 +942,6 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) dev_err_ratelimited(disk_to_dev(nbd->disk), "Attempted send on invalid socket\n"); nbd_config_put(nbd); - blk_mq_start_request(req); return -EINVAL; } cmd->status = BLK_STS_OK; @@ -967,7 +965,6 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index) */ sock_shutdown(nbd); nbd_config_put(nbd); - blk_mq_start_request(req); return -EIO; } goto again; From patchwork Wed Sep 15 09:20:09 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12495817 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 83CEBC433FE for ; Wed, 15 Sep 2021 09:10:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C0FC61246 for ; Wed, 15 Sep 2021 09:10:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237194AbhIOJLm (ORCPT ); Wed, 15 Sep 2021 05:11:42 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:19983 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237174AbhIOJLk (ORCPT ); Wed, 15 Sep 2021 05:11:40 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4H8Z864ccYzbkQ5; Wed, 15 Sep 2021 17:06:14 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:20 +0800 Received: from huawei.com (10.175.127.227) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:20 +0800 From: Yu Kuai To: , , , CC: , , , , Subject: [PATCH v7 5/6] nbd: partition nbd_read_stat() into nbd_read_reply() and nbd_handle_reply() Date: Wed, 15 Sep 2021 17:20:09 +0800 Message-ID: <20210915092010.2087371-6-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210915092010.2087371-1-yukuai3@huawei.com> References: <20210915092010.2087371-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Prepare to fix uaf in nbd_read_stat(), no functional changes. Signed-off-by: Yu Kuai --- drivers/block/nbd.c | 76 +++++++++++++++++++++++++++------------------ 1 file changed, 45 insertions(+), 31 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 22c91d8901f6..9a7bbf8ebe74 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -694,38 +694,45 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) return 0; } -/* NULL returned = something went wrong, inform userspace */ -static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index) +static int nbd_read_reply(struct nbd_device *nbd, int index, + struct nbd_reply *reply) { - struct nbd_config *config = nbd->config; - int result; - struct nbd_reply reply; - struct nbd_cmd *cmd; - struct request *req = NULL; - u64 handle; - u16 hwq; - u32 tag; - struct kvec iov = {.iov_base = &reply, .iov_len = sizeof(reply)}; + struct kvec iov = {.iov_base = reply, .iov_len = sizeof(*reply)}; struct iov_iter to; - int ret = 0; + int result; - reply.magic = 0; - iov_iter_kvec(&to, READ, &iov, 1, sizeof(reply)); + reply->magic = 0; + iov_iter_kvec(&to, READ, &iov, 1, sizeof(*reply)); result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL); - if (result <= 0) { - if (!nbd_disconnected(config)) + if (result < 0) { + if (!nbd_disconnected(nbd->config)) dev_err(disk_to_dev(nbd->disk), "Receive control failed (result %d)\n", result); - return ERR_PTR(result); + return result; } - if (ntohl(reply.magic) != NBD_REPLY_MAGIC) { + if (ntohl(reply->magic) != NBD_REPLY_MAGIC) { dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n", - (unsigned long)ntohl(reply.magic)); - return ERR_PTR(-EPROTO); + (unsigned long)ntohl(reply->magic)); + return -EPROTO; } - memcpy(&handle, reply.handle, sizeof(handle)); + return 0; +} + +/* NULL returned = something went wrong, inform userspace */ +static struct nbd_cmd *nbd_handle_reply(struct nbd_device *nbd, int index, + struct nbd_reply *reply) +{ + int result; + struct nbd_cmd *cmd; + struct request *req = NULL; + u64 handle; + u16 hwq; + u32 tag; + int ret = 0; + + memcpy(&handle, reply->handle, sizeof(handle)); tag = nbd_handle_to_tag(handle); hwq = blk_mq_unique_tag_to_hwq(tag); if (hwq < nbd->tag_set.nr_hw_queues) @@ -768,9 +775,9 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index) ret = -ENOENT; goto out; } - if (ntohl(reply.error)) { + if (ntohl(reply->error)) { dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n", - ntohl(reply.error)); + ntohl(reply->error)); cmd->status = BLK_STS_IOERR; goto out; } @@ -779,6 +786,7 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index) if (rq_data_dir(req) != WRITE) { struct req_iterator iter; struct bio_vec bvec; + struct iov_iter to; rq_for_each_segment(bvec, req, iter) { iov_iter_bvec(&to, READ, &bvec, 1, bvec.bv_len); @@ -792,7 +800,7 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index) * and let the timeout stuff handle resubmitting * this request onto another connection. */ - if (nbd_disconnected(config)) { + if (nbd_disconnected(nbd->config)) { cmd->status = BLK_STS_IOERR; goto out; } @@ -816,24 +824,30 @@ static void recv_work(struct work_struct *work) work); struct nbd_device *nbd = args->nbd; struct nbd_config *config = nbd->config; + struct nbd_sock *nsock; struct nbd_cmd *cmd; struct request *rq; while (1) { - cmd = nbd_read_stat(nbd, args->index); - if (IS_ERR(cmd)) { - struct nbd_sock *nsock = config->socks[args->index]; + struct nbd_reply reply; - mutex_lock(&nsock->tx_lock); - nbd_mark_nsock_dead(nbd, nsock, 1); - mutex_unlock(&nsock->tx_lock); + if (nbd_read_reply(nbd, args->index, &reply)) + break; + + cmd = nbd_handle_reply(nbd, args->index, &reply); + if (IS_ERR(cmd)) break; - } rq = blk_mq_rq_from_pdu(cmd); if (likely(!blk_should_fake_timeout(rq->q))) blk_mq_complete_request(rq); } + + nsock = config->socks[args->index]; + mutex_lock(&nsock->tx_lock); + nbd_mark_nsock_dead(nbd, nsock, 1); + mutex_unlock(&nsock->tx_lock); + nbd_config_put(nbd); atomic_dec(&config->recv_threads); wake_up(&config->recv_wq); From patchwork Wed Sep 15 09:20:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12495823 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 8D00EC433F5 for ; Wed, 15 Sep 2021 09:10:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 776986124F for ; Wed, 15 Sep 2021 09:10:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237258AbhIOJLx (ORCPT ); Wed, 15 Sep 2021 05:11:53 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:15421 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237229AbhIOJLp (ORCPT ); Wed, 15 Sep 2021 05:11:45 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4H8Z8B1nThzRCTW; Wed, 15 Sep 2021 17:06:18 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:21 +0800 Received: from huawei.com (10.175.127.227) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Wed, 15 Sep 2021 17:10:20 +0800 From: Yu Kuai To: , , , CC: , , , , Subject: [PATCH v7 6/6] nbd: fix uaf in nbd_handle_reply() Date: Wed, 15 Sep 2021 17:20:10 +0800 Message-ID: <20210915092010.2087371-7-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210915092010.2087371-1-yukuai3@huawei.com> References: <20210915092010.2087371-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org There is a problem that nbd_handle_reply() might access freed request: 1) At first, a normal io is submitted and completed with scheduler: internel_tag = blk_mq_get_tag -> get tag from sched_tags blk_mq_rq_ctx_init sched_tags->rq[internel_tag] = sched_tag->static_rq[internel_tag] ... blk_mq_get_driver_tag __blk_mq_get_driver_tag -> get tag from tags tags->rq[tag] = sched_tag->static_rq[internel_tag] So, both tags->rq[tag] and sched_tags->rq[internel_tag] are pointing to the request: sched_tags->static_rq[internal_tag]. Even if the io is finished. 2) nbd server send a reply with random tag directly: recv_work nbd_handle_reply blk_mq_tag_to_rq(tags, tag) rq = tags->rq[tag] 3) if the sched_tags->static_rq is freed: blk_mq_sched_free_requests blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i) -> step 2) access rq before clearing rq mapping blk_mq_clear_rq_mapping(set, tags, hctx_idx); __free_pages() -> rq is freed here 4) Then, nbd continue to use the freed request in nbd_handle_reply Fix the problem by get 'q_usage_counter' before blk_mq_tag_to_rq(), thus request is ensured not to be freed because 'q_usage_counter' is not zero. Signed-off-by: Yu Kuai --- drivers/block/nbd.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 9a7bbf8ebe74..3e8b70b5d4f9 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -824,6 +824,7 @@ static void recv_work(struct work_struct *work) work); struct nbd_device *nbd = args->nbd; struct nbd_config *config = nbd->config; + struct request_queue *q = nbd->disk->queue; struct nbd_sock *nsock; struct nbd_cmd *cmd; struct request *rq; @@ -834,7 +835,24 @@ static void recv_work(struct work_struct *work) if (nbd_read_reply(nbd, args->index, &reply)) break; + /* + * Grab ref of q_usage_counter can prevent request being freed + * during nbd_handle_reply(). If q_usage_counter is zero, then + * no request is inflight, which means something is wrong since + * we expect to find a request to complete here. + */ + if (!percpu_ref_tryget(&q->q_usage_counter)) { + dev_err(disk_to_dev(nbd->disk), "%s: no io inflight\n", + __func__); + break; + } + cmd = nbd_handle_reply(nbd, args->index, &reply); + /* + * It's safe to drop ref before request completion, inflight + * request will ensure q_usage_counter won't be zero. + */ + percpu_ref_put(&q->q_usage_counter); if (IS_ERR(cmd)) break;