From patchwork Tue Nov 2 01:52:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "yebin (H)" X-Patchwork-Id: 12597733 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E1B8C433FE for ; Tue, 2 Nov 2021 01:40:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 334B1603E8 for ; Tue, 2 Nov 2021 01:40:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230015AbhKBBmd (ORCPT ); Mon, 1 Nov 2021 21:42:33 -0400 Received: from szxga08-in.huawei.com ([45.249.212.255]:26143 "EHLO szxga08-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229679AbhKBBma (ORCPT ); Mon, 1 Nov 2021 21:42:30 -0400 Received: from dggeme754-chm.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4HjswX7274z1DJ5m; Tue, 2 Nov 2021 09:37:48 +0800 (CST) Received: from huawei.com (10.175.127.227) by dggeme754-chm.china.huawei.com (10.3.19.100) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.15; Tue, 2 Nov 2021 09:39:51 +0800 From: Ye Bin To: , , , CC: , Yu Kuai Subject: [PATCH -next v4 1/4] nbd: fix max value for 'first_minor' Date: Tue, 2 Nov 2021 09:52:34 +0800 Message-ID: <20211102015237.2309763-2-yebin10@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211102015237.2309763-1-yebin10@huawei.com> References: <20211102015237.2309763-1-yebin10@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 dggeme754-chm.china.huawei.com (10.3.19.100) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Yu Kuai commit b1a811633f73 ("block: nbd: add sanity check for first_minor") checks that 'first_minor' should not be greater than 0xff, which is wrong. Whitout the commit, the details that when user pass 0x100000, it ends up create sysfs dir "/sys/block/43:0" are as follows: nbd_dev_add disk->first_minor = index << part_shift -> default part_shift is 5, first_minor is 0x2000000 device_add_disk ddev->devt = MKDEV(disk->major, disk->first_minor) -> (0x2b << 20) | (0x2000000) = 0x2b00000 device_add device_create_sys_dev_entry format_dev_t sprintf(buffer, "%u:%u", MAJOR(dev), MINOR(dev)); -> got 43:0 sysfs_create_link -> /sys/block/43:0 By the way, with the wrong fix, when part_shift is the default value, only 8 ndb devices can be created since 8 << 5 is greater than 0xff. Since the max bits for 'first_minor' should be the same as what MKDEV() does, which is 20. Change the upper bound of 'first_minor' from 0xff to 0xfffff. Fixes: b1a811633f73 ("block: nbd: add sanity check for first_minor") Signed-off-by: Yu Kuai --- drivers/block/nbd.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index b47b2a87ae8f..678ee2688f63 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1803,11 +1803,11 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs) disk->major = NBD_MAJOR; /* Too big first_minor can cause duplicate creation of - * sysfs files/links, since first_minor will be truncated to - * byte in __device_add_disk(). + * sysfs files/links, since MKDEV() expect that the max bits of + * first_minor is 20. */ disk->first_minor = index << part_shift; - if (disk->first_minor > 0xff) { + if (disk->first_minor > MINORMASK) { err = -EINVAL; goto out_free_idr; }