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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_1 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 9B3BAC47247 for ; Tue, 5 May 2020 03:00:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7EE4B206CC for ; Tue, 5 May 2020 03:00:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726286AbgEEDAU (ORCPT ); Mon, 4 May 2020 23:00:20 -0400 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]:46038 "EHLO out30-132.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726516AbgEEDAU (ORCPT ); Mon, 4 May 2020 23:00:20 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07425;MF=xiaoguang.wang@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0TxX9D1H_1588647587; Received: from 30.39.165.186(mailfrom:xiaoguang.wang@linux.alibaba.com fp:SMTPD_---0TxX9D1H_1588647587) by smtp.aliyun-inc.com(127.0.0.1); Tue, 05 May 2020 10:59:47 +0800 Subject: Re: [PATCH] io_uring: handle -EFAULT properly in io_uring_setup() To: Pavel Begunkov , io-uring@vger.kernel.org Cc: axboe@kernel.dk, joseph.qi@linux.alibaba.com References: <20200504135328.29396-1-xiaoguang.wang@linux.alibaba.com> <8f6b82d4-7e52-e25a-4f05-f16e51854df1@gmail.com> From: Xiaoguang Wang Message-ID: Date: Tue, 5 May 2020 10:59:46 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <8f6b82d4-7e52-e25a-4f05-f16e51854df1@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org hi, > On 04/05/2020 16:53, Xiaoguang Wang wrote: >> If copy_to_user() in io_uring_setup() failed, we'll leak many kernel >> resources, which could be reproduced by using mprotect to set params > > At least it recycles everything upon killing the process, so that's rather not > notifying a user about a successfully installed fd. Good catch Yeah, I'll add more explanation in commit message, thanks. Regards, Xiaoguang Wnag > > >> to PROT_READ. To fix this issue, refactor io_uring_create() a bit to >> let it return 'struct io_ring_ctx *', then when copy_to_user() failed, >> we can free kernel resource properly. >> >> Signed-off-by: Xiaoguang Wang >> --- >> fs/io_uring.c | 45 ++++++++++++++++++++++++--------------------- >> 1 file changed, 24 insertions(+), 21 deletions(-) >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index 0b91b0631173..a19885dee621 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -7761,7 +7761,8 @@ static int io_uring_get_fd(struct io_ring_ctx *ctx) >> return ret; >> } >> >> -static int io_uring_create(unsigned entries, struct io_uring_params *p) >> +static struct io_ring_ctx *io_uring_create(unsigned entries, >> + struct io_uring_params *p) >> { >> struct user_struct *user = NULL; >> struct io_ring_ctx *ctx; >> @@ -7769,10 +7770,10 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) >> int ret; >> >> if (!entries) >> - return -EINVAL; >> + return ERR_PTR(-EINVAL); >> if (entries > IORING_MAX_ENTRIES) { >> if (!(p->flags & IORING_SETUP_CLAMP)) >> - return -EINVAL; >> + return ERR_PTR(-EINVAL); >> entries = IORING_MAX_ENTRIES; >> } >> >> @@ -7792,10 +7793,10 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) >> * any cq vs sq ring sizing. >> */ >> if (p->cq_entries < p->sq_entries) >> - return -EINVAL; >> + return ERR_PTR(-EINVAL); >> if (p->cq_entries > IORING_MAX_CQ_ENTRIES) { >> if (!(p->flags & IORING_SETUP_CLAMP)) >> - return -EINVAL; >> + return ERR_PTR(-EINVAL); >> p->cq_entries = IORING_MAX_CQ_ENTRIES; >> } >> p->cq_entries = roundup_pow_of_two(p->cq_entries); >> @@ -7811,7 +7812,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) >> ring_pages(p->sq_entries, p->cq_entries)); >> if (ret) { >> free_uid(user); >> - return ret; >> + return ERR_PTR(ret); >> } >> } >> >> @@ -7821,7 +7822,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) >> io_unaccount_mem(user, ring_pages(p->sq_entries, >> p->cq_entries)); >> free_uid(user); >> - return -ENOMEM; >> + return ERR_PTR(-ENOMEM); >> } >> ctx->compat = in_compat_syscall(); >> ctx->account_mem = account_mem; >> @@ -7853,22 +7854,14 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) >> p->cq_off.overflow = offsetof(struct io_rings, cq_overflow); >> p->cq_off.cqes = offsetof(struct io_rings, cqes); >> >> - /* >> - * Install ring fd as the very last thing, so we don't risk someone >> - * having closed it before we finish setup >> - */ >> - ret = io_uring_get_fd(ctx); >> - if (ret < 0) >> - goto err; >> - >> p->features = IORING_FEAT_SINGLE_MMAP | IORING_FEAT_NODROP | >> IORING_FEAT_SUBMIT_STABLE | IORING_FEAT_RW_CUR_POS | >> IORING_FEAT_CUR_PERSONALITY | IORING_FEAT_FAST_POLL; >> trace_io_uring_create(ret, ctx, p->sq_entries, p->cq_entries, p->flags); >> - return ret; >> + return ctx; >> err: >> io_ring_ctx_wait_and_kill(ctx); >> - return ret; >> + return ERR_PTR(ret); >> } >> >> /* >> @@ -7878,6 +7871,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) >> */ >> static long io_uring_setup(u32 entries, struct io_uring_params __user *params) >> { >> + struct io_ring_ctx *ctx; >> struct io_uring_params p; >> long ret; >> int i; >> @@ -7894,12 +7888,21 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params) >> IORING_SETUP_CLAMP | IORING_SETUP_ATTACH_WQ)) >> return -EINVAL; >> >> - ret = io_uring_create(entries, &p); >> - if (ret < 0) >> - return ret; >> + ctx = io_uring_create(entries, &p); >> + if (IS_ERR(ctx)) >> + return PTR_ERR(ctx); >> >> - if (copy_to_user(params, &p, sizeof(p))) >> + if (copy_to_user(params, &p, sizeof(p))) { >> + io_ring_ctx_wait_and_kill(ctx); >> return -EFAULT; >> + } >> + /* >> + * Install ring fd as the very last thing, so we don't risk someone >> + * having closed it before we finish setup >> + */ >> + ret = io_uring_get_fd(ctx); >> + if (ret < 0) >> + io_ring_ctx_wait_and_kill(ctx); >> >> return ret; >> } >> >