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 B0E19C64EC7 for ; Wed, 1 Mar 2023 03:49:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229900AbjCADtC (ORCPT ); Tue, 28 Feb 2023 22:49:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229761AbjCADs4 (ORCPT ); Tue, 28 Feb 2023 22:48:56 -0500 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C3D8173E; Tue, 28 Feb 2023 19:48:48 -0800 (PST) Received: from kwepemm600002.china.huawei.com (unknown [172.30.72.56]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4PRKpW30wTzKmTh; Wed, 1 Mar 2023 11:43:47 +0800 (CST) Received: from [10.174.178.159] (10.174.178.159) by kwepemm600002.china.huawei.com (7.193.23.29) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Wed, 1 Mar 2023 11:48:45 +0800 Message-ID: <9ddd30ab-164b-21c8-2f68-4ed13377bf68@huawei.com> Date: Wed, 1 Mar 2023 11:48:44 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH-next] nbd: fix incomplete validation of ioctl arg To: , CC: , , , , , , References: <20230206145805.2645671-1-zhongjinghua@huawei.com> From: zhongjinghua In-Reply-To: <20230206145805.2645671-1-zhongjinghua@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.159] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemm600002.china.huawei.com (7.193.23.29) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ping... Hello, Anyone looking this? 在 2023/2/6 22:58, Zhong Jinghua 写道: > We tested and found an alarm caused by nbd_ioctl arg without verification. > The UBSAN warning calltrace like below: > > UBSAN: Undefined behaviour in fs/buffer.c:1709:35 > signed integer overflow: > -9223372036854775808 - 1 cannot be represented in type 'long long int' > CPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1 > Hardware name: linux,dummy-virt (DT) > Call trace: > dump_backtrace+0x0/0x3f0 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+0x170/0x1dc lib/dump_stack.c:118 > ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161 > handle_overflow+0x188/0x1dc lib/ubsan.c:192 > __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206 > __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709 > block_write_full_page+0x1f0/0x280 fs/buffer.c:2934 > blkdev_writepage+0x34/0x40 fs/block_dev.c:607 > __writepage+0x68/0xe8 mm/page-writeback.c:2305 > write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240 > generic_writepages+0xdc/0x148 mm/page-writeback.c:2329 > blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114 > do_writepages+0xd4/0x250 mm/page-writeback.c:2344 > > The reason for triggering this warning is __block_write_full_page() > -> i_size_read(inode) - 1 overflow. > inode->i_size is assigned in __nbd_ioctl() -> nbd_set_size() -> bytesize. > We think it is necessary to limit the size of arg to prevent errors. > > Moreover, __nbd_ioctl() -> nbd_add_socket(), arg will be cast to int. > Assuming the value of arg is 0x80000000000000001) (on a 64-bit machine), > it will become 1 after the coercion, which will return unexpected results. > > Fix it by adding checks to prevent passing in too large numbers. > > Signed-off-by: Zhong Jinghua > --- > drivers/block/nbd.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c > index 592cfa8b765a..e1c954094b6c 100644 > --- a/drivers/block/nbd.c > +++ b/drivers/block/nbd.c > @@ -325,6 +325,9 @@ static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize, > if (blk_validate_block_size(blksize)) > return -EINVAL; > > + if (bytesize < 0) > + return -EINVAL; > + > nbd->config->bytesize = bytesize; > nbd->config->blksize_bits = __ffs(blksize); > > @@ -1111,6 +1114,9 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg, > struct nbd_sock *nsock; > int err; > > + /* Arg will be cast to int, check it to avoid overflow */ > + if (arg > INT_MAX) > + return -EINVAL; > sock = nbd_get_socket(nbd, arg, &err); > if (!sock) > return err;