From mboxrd@z Thu Jan 1 00:00:00 1970 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0283EC433F5 for ; Thu, 17 Mar 2022 13:05:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232690AbiCQNGx (ORCPT ); Thu, 17 Mar 2022 09:06:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33220 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229841AbiCQNGu (ORCPT ); Thu, 17 Mar 2022 09:06:50 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 428A31557CA; Thu, 17 Mar 2022 06:05:33 -0700 (PDT) Received: from dggeme756-chm.china.huawei.com (unknown [172.30.72.53]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4KK6hy4lDNz9smw; Thu, 17 Mar 2022 21:01:22 +0800 (CST) Received: from [10.174.176.103] (10.174.176.103) by dggeme756-chm.china.huawei.com (10.3.19.102) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.21; Thu, 17 Mar 2022 21:05:11 +0800 Message-ID: <8139ea99-09fa-eb84-e9ef-f1fb470b5b88@huawei.com> Date: Thu, 17 Mar 2022 21:05:11 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.4.1 Subject: Re: [PATCH -next] nbd: fix possible overflow on 'first_minor' in nbd_dev_add() From: "zhangwensheng (E)" To: , CC: , , , References: <20220310093224.4002895-1-zhangwensheng5@huawei.com> <0e5faf35-5adb-3ea1-9f7f-7c4f61a623b2@huawei.com> In-Reply-To: <0e5faf35-5adb-3ea1-9f7f-7c4f61a623b2@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.176.103] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggeme756-chm.china.huawei.com (10.3.19.102) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org friendly ping... 在 2022/3/11 10:43, zhangwensheng (E) 写道: > friendly ping... > > 在 2022/3/10 17:32, Zhang Wensheng 写道: >> When 'index' is a big numbers, it may become negative which forced >> to 'int'. then 'index << part_shift' might overflow to a positive >> value that is not greater than '0xfffff', then sysfs might complains >> about duplicate creation. Because of this, move the 'index' judgment >> to the front will fix it and be better. >> >> Fixes: b0d9111a2d53 ("nbd: use an idr to keep track of nbd devices") >> Fixes: 940c264984fd ("nbd: fix possible overflow for 'first_minor' in >> nbd_dev_add()") >> Signed-off-by: Zhang Wensheng >> --- >>   drivers/block/nbd.c | 24 ++++++++++++------------ >>   1 file changed, 12 insertions(+), 12 deletions(-) >> >> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c >> index 5a1f98494ddd..b3cdfc0ffb98 100644 >> --- a/drivers/block/nbd.c >> +++ b/drivers/block/nbd.c >> @@ -1800,17 +1800,6 @@ static struct nbd_device *nbd_dev_add(int >> index, unsigned int refs) >>       refcount_set(&nbd->refs, 0); >>       INIT_LIST_HEAD(&nbd->list); >>       disk->major = NBD_MAJOR; >> - >> -    /* Too big first_minor can cause duplicate creation of >> -     * sysfs files/links, since index << part_shift might overflow, or >> -     * MKDEV() expect that the max bits of first_minor is 20. >> -     */ >> -    disk->first_minor = index << part_shift; >> -    if (disk->first_minor < index || disk->first_minor > MINORMASK) { >> -        err = -EINVAL; >> -        goto out_free_work; >> -    } >> - >>       disk->minors = 1 << part_shift; >>       disk->fops = &nbd_fops; >>       disk->private_data = nbd; >> @@ -1915,8 +1904,19 @@ static int nbd_genl_connect(struct sk_buff >> *skb, struct genl_info *info) >>       if (!netlink_capable(skb, CAP_SYS_ADMIN)) >>           return -EPERM; >>   -    if (info->attrs[NBD_ATTR_INDEX]) >> +    if (info->attrs[NBD_ATTR_INDEX]) { >>           index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]); >> + >> +        /* >> +         * Too big first_minor can cause duplicate creation of >> +         * sysfs files/links, since index << part_shift might >> overflow, or >> +         * MKDEV() expect that the max bits of first_minor is 20. >> +         */ >> +        if (index < 0 || index > MINORMASK >> part_shift) { >> +            printk(KERN_ERR "nbd: illegal input index %d\n", index); >> +            return -EINVAL; >> +        } >> +    } >>       if (!info->attrs[NBD_ATTR_SOCKETS]) { >>           printk(KERN_ERR "nbd: must specify at least one socket\n"); >>           return -EINVAL; > .