From patchwork Tue Aug 24 14:12:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12455137 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 4D0A1C4320E for ; Tue, 24 Aug 2021 14:02:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3855E6127B for ; Tue, 24 Aug 2021 14:02:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237591AbhHXODA (ORCPT ); Tue, 24 Aug 2021 10:03:00 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:8922 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234695AbhHXOC7 (ORCPT ); Tue, 24 Aug 2021 10:02:59 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Gv9fw1YDcz8tnd; Tue, 24 Aug 2021 21:58:00 +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 15.1.2176.2; Tue, 24 Aug 2021 22:02:08 +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 15.1.2176.2; Tue, 24 Aug 2021 22:02:07 +0800 From: Yu Kuai To: , , , CC: , , , , Subject: [PATCH v3 1/5] blk-mq: add a new interface to get request by tag Date: Tue, 24 Aug 2021 22:12:23 +0800 Message-ID: <20210824141227.808340-2-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210824141227.808340-1-yukuai3@huawei.com> References: <20210824141227.808340-1-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 Ming Lei had fixed the request uaf while iterating tags in commit bd63141d585b ("blk-mq: clear stale request in tags->rq[] before freeing one request pool"). However, hctx->tags->rq[] will point to hctx->sched_tags->static_rq[] in blk_mq_get_driver_tag(), and blk_mq_tag_to_rq() can access such request in some drivers. Generally it won't be a problem if the driver can make sure to get drivet tag before calling blk_mq_tag_to_rq(). However, nbd will do such thing once it receive a reply message from server, and there isn't any mechanism to protect that it won't handle the reply message without a corresponding request message. Thus add new interface to make sure it won't return a freed request, and then nbd can check if it had sent the corresponding request message. Signed-off-by: Yu Kuai --- block/blk-mq-tag.c | 37 +++++++++++++++++++++++++++++++++++++ block/blk-mq.c | 1 + block/blk-mq.h | 1 - include/linux/blk-mq.h | 4 ++++ 4 files changed, 42 insertions(+), 1 deletion(-) diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 86f87346232a..ddb159414661 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -652,3 +652,40 @@ u32 blk_mq_unique_tag(struct request *rq) (rq->tag & BLK_MQ_UNIQUE_TAG_MASK); } EXPORT_SYMBOL(blk_mq_unique_tag); + + +/** + * blk_mq_get_rq_by_tag - if the request that is represented by the tag is + * not idle, increment it's reference and then return it. Otherwise return + * NULL. + * + * @tags: the tags we are looking from + * @tag: the tag that represents the request + */ +struct request *blk_mq_get_rq_by_tag(struct blk_mq_tags *tags, + unsigned int tag) +{ + unsigned long flags; + struct request *rq; + + /* hold lock to prevent accessing freed request by tag */ + spin_lock_irqsave(&tags->lock, flags); + rq = blk_mq_tag_to_rq(tags, tag); + if (!rq) + goto out_unlock; + + if (!refcount_inc_not_zero(&rq->ref)) { + rq = NULL; + goto out_unlock; + } + + if (!blk_mq_request_started(rq)) { + blk_mq_put_rq_ref(rq); + rq = NULL; + } + +out_unlock: + spin_unlock_irqrestore(&tags->lock, flags); + return rq; +} +EXPORT_SYMBOL(blk_mq_get_rq_by_tag); diff --git a/block/blk-mq.c b/block/blk-mq.c index 0b3d3e2acb6a..c756a26ed92d 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -916,6 +916,7 @@ void blk_mq_put_rq_ref(struct request *rq) else if (refcount_dec_and_test(&rq->ref)) __blk_mq_free_request(rq); } +EXPORT_SYMBOL_GPL(blk_mq_put_rq_ref); static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx, struct request *rq, void *priv, bool reserved) diff --git a/block/blk-mq.h b/block/blk-mq.h index d08779f77a26..20ef743a3ff6 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -47,7 +47,6 @@ void blk_mq_add_to_requeue_list(struct request *rq, bool at_head, void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list); struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *start); -void blk_mq_put_rq_ref(struct request *rq); /* * Internal helpers for allocating/freeing the request map diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 22215db36122..ccd8fc4a0bdb 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -641,4 +641,8 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio); void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx, struct lock_class_key *key); +struct request *blk_mq_get_rq_by_tag(struct blk_mq_tags *tags, + unsigned int tag); +void blk_mq_put_rq_ref(struct request *rq); + #endif