From patchwork Mon Mar 1 02:14:43 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yufen Yu X-Patchwork-Id: 12108647 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 E9110C433E9 for ; Mon, 1 Mar 2021 02:10:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AEEA564E6B for ; Mon, 1 Mar 2021 02:10:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231670AbhCACKu (ORCPT ); Sun, 28 Feb 2021 21:10:50 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:13010 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231669AbhCACKs (ORCPT ); Sun, 28 Feb 2021 21:10:48 -0500 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DpkFM0cLKzjTZb; Mon, 1 Mar 2021 10:08:23 +0800 (CST) Received: from huawei.com (10.175.101.6) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.498.0; Mon, 1 Mar 2021 10:09:53 +0800 From: Yufen Yu To: , CC: , , , , Subject: [RFC PATCH 1/2] blk-mq: test tags bitmap before get request Date: Sun, 28 Feb 2021 21:14:43 -0500 Message-ID: <20210301021444.4134047-2-yuyufen@huawei.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20210301021444.4134047-1-yuyufen@huawei.com> References: <20210301021444.4134047-1-yuyufen@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.101.6] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org For now, we set hctx->tags->rqs[i] when get driver tag successfully. The request either comes from sched_tags->static_rqs[] with scheduler, or comes from tags->static_rqs[] with no scheduler. But, the value won't be clear when put driver tag. Thus, tags->rqs[i] still remain old request. We can free these sched_tags->static_rqs[] requests when switch elevator, update nr_requests or update nr_hw_queues. After that, unexpected access of tags->rqs[i] may cause use-after-free crash. For example, we reported use-after-free of request in nbd device by syzkaller: BUG: KASAN: use-after-free in blk_mq_request_started+0x24/0x40 block/blk-mq.c:644 Read of size 4 at addr ffff80036b77f9d4 by task kworker/u9:0/10086 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:2156 worker_thread+0x80/0x9d0 kernel/workqueue.c:2311 kthread+0x1d8/0x1e0 kernel/kthread.c:255 ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1174 The syzkaller test program sended a reply package to client without client sending request. After receiving the package, recv_work() try to get the remained request in tags->rqs[] by tag, which have been free. To avoid this type of problem, we may need to ensure the request valid when get it by tag. Signed-off-by: Yufen Yu --- block/blk-mq.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index d4d7c1caa439..5362a7958b74 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -836,9 +836,17 @@ void blk_mq_delay_kick_requeue_list(struct request_queue *q, } EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list); +static int blk_mq_test_tag_bit(struct blk_mq_tags *tags, unsigned int tag) +{ + if (!blk_mq_tag_is_reserved(tags, tag)) + return sbitmap_test_bit(&tags->bitmap_tags->sb, tag); + else + return sbitmap_test_bit(&tags->breserved_tags->sb, tag); +} + struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag) { - if (tag < tags->nr_tags) { + if (tag < tags->nr_tags && blk_mq_test_tag_bit(tags, tag)) { prefetch(tags->rqs[tag]); return tags->rqs[tag]; }