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 B7E6EC433FE for ; Fri, 11 Mar 2022 02:43:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345713AbiCKCoW (ORCPT ); Thu, 10 Mar 2022 21:44:22 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53438 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240820AbiCKCoQ (ORCPT ); Thu, 10 Mar 2022 21:44:16 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0B1F1F3907; Thu, 10 Mar 2022 18:43:14 -0800 (PST) Received: from dggeme756-chm.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KF9DC1HJPzBrKj; Fri, 11 Mar 2022 10:41:15 +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; Fri, 11 Mar 2022 10:43:11 +0800 Message-ID: <0e5faf35-5adb-3ea1-9f7f-7c4f61a623b2@huawei.com> Date: Fri, 11 Mar 2022 10:43:10 +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() To: , CC: , , , References: <20220310093224.4002895-1-zhangwensheng5@huawei.com> From: "zhangwensheng (E)" In-Reply-To: <20220310093224.4002895-1-zhangwensheng5@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.176.103] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) 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 2022/3/10 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;