From patchwork Sun Aug 8 03:17:52 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12424651 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 6A9E8C432BE for ; Sun, 8 Aug 2021 03:07:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4BE9160EE8 for ; Sun, 8 Aug 2021 03:07:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230169AbhHHDHd (ORCPT ); Sat, 7 Aug 2021 23:07:33 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:8376 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229977AbhHHDHc (ORCPT ); Sat, 7 Aug 2021 23:07:32 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Gj3tq4MLNz8477; Sun, 8 Aug 2021 11:03:15 +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 15.1.2176.2; Sun, 8 Aug 2021 11:07:09 +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; Sun, 8 Aug 2021 11:07:09 +0800 From: Yu Kuai To: , , CC: , , , , Subject: [PATCH 2/2] nbd: hold tags->lock to prevent access freed request through blk_mq_tag_to_rq() Date: Sun, 8 Aug 2021 11:17:52 +0800 Message-ID: <20210808031752.579882-3-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210808031752.579882-1-yukuai3@huawei.com> References: <20210808031752.579882-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) 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 Our test reported a uaf problem: Read of size 4 at addr ffff80036b790b54 by task kworker/u9:1/31105 Workqueue: knbd0-recv recv_work Call trace: dump_backtrace+0x0/0x310 arch/arm64/kernel/time.c:78 show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x144/0x1b4 lib/dump_stack.c:118 print_address_description+0x68/0x2d0 mm/kasan/report.c:253 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x134/0x2f0 mm/kasan/report.c:409 check_memory_region_inline mm/kasan/kasan.c:260 [inline] __asan_load4+0x88/0xb0 mm/kasan/kasan.c:699 __read_once_size include/linux/compiler.h:193 [inline] blk_mq_rq_state block/blk-mq.h:106 [inline] blk_mq_request_started+0x24/0x40 block/blk-mq.c:644 nbd_read_stat drivers/block/nbd.c:670 [inline] recv_work+0x1bc/0x890 drivers/block/nbd.c:749 process_one_work+0x3ec/0x9e0 kernel/workqueue.c:2147 worker_thread+0x80/0x9d0 kernel/workqueue.c:2302 kthread+0x1d8/0x1e0 kernel/kthread.c:255 ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1174 This is because tags->static_rq can be freed without clearing tags->rq, Ming Lei had fixed the problem while itering tags, howerver, the problem still exist in blk_mq_tag_to_rq(). Thus fix the problem by holding tags->lock, so that tags->rq can be cleared before tags->static_rq is freed. Signed-off-by: Yu Kuai --- drivers/block/nbd.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index c38317979f74..c7ca16f0adbd 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -712,12 +712,22 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index) 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) - req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq], - blk_mq_unique_tag_to_tag(tag)); - if (!req || !blk_mq_request_started(req)) { - dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n", - tag, req); + if (hwq < nbd->tag_set.nr_hw_queues) { + unsigned long flags; + struct blk_mq_tags *tags = nbd->tag_set.tags[hwq]; + + blk_mq_tags_lock(tags, &flags); + req = blk_mq_tag_to_rq(tags, blk_mq_unique_tag_to_tag(tag)); + if (!blk_mq_request_started(req)) { + dev_err(disk_to_dev(nbd->disk), "Request not started (%d) %p\n", + tag, req); + req = NULL; + } + blk_mq_tags_unlock(tags, &flags); + } + + if (!req) { + dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d)\n", tag); return ERR_PTR(-ENOENT); } trace_nbd_header_received(req, handle);