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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 E5737C4361B for ; Fri, 11 Dec 2020 15:40:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9DC6923B85 for ; Fri, 11 Dec 2020 15:40:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437563AbgLKPCd (ORCPT ); Fri, 11 Dec 2020 10:02:33 -0500 Received: from out30-54.freemail.mail.aliyun.com ([115.124.30.54]:52255 "EHLO out30-54.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2437549AbgLKPCQ (ORCPT ); Fri, 11 Dec 2020 10:02:16 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=xiaoguang.wang@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0UIG5c9o_1607698889; Received: from 30.15.214.129(mailfrom:xiaoguang.wang@linux.alibaba.com fp:SMTPD_---0UIG5c9o_1607698889) by smtp.aliyun-inc.com(127.0.0.1); Fri, 11 Dec 2020 23:01:29 +0800 Subject: Re: [PATCH] io_uring: always let io_iopoll_complete() complete polled io. To: Pavel Begunkov , io-uring@vger.kernel.org Cc: axboe@kernel.dk, joseph.qi@linux.alibaba.com References: <20201202113151.1680-1-xiaoguang.wang@linux.alibaba.com> From: Xiaoguang Wang Message-ID: <1249ded8-335a-b441-0207-db943b8a93c8@linux.alibaba.com> Date: Fri, 11 Dec 2020 22:59:52 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org hi Pavel, > On 02/12/2020 11:31, Xiaoguang Wang wrote: >> Abaci Fuzz reported a double-free or invalid-free BUG in io_commit_cqring(): >> [ 95.504842] BUG: KASAN: double-free or invalid-free in io_commit_cqring+0x3ec/0x8e0 >> [ 95.505921] >> [ 95.506225] CPU: 0 PID: 4037 Comm: io_wqe_worker-0 Tainted: G B >> W 5.10.0-rc5+ #1 >> [ 95.507434] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 >> [ 95.508248] Call Trace: >> [ 95.508683] dump_stack+0x107/0x163 >> [ 95.509323] ? io_commit_cqring+0x3ec/0x8e0 >> [ 95.509982] print_address_description.constprop.0+0x3e/0x60 >> [ 95.510814] ? vprintk_func+0x98/0x140 >> [ 95.511399] ? io_commit_cqring+0x3ec/0x8e0 >> [ 95.512036] ? io_commit_cqring+0x3ec/0x8e0 >> [ 95.512733] kasan_report_invalid_free+0x51/0x80 >> [ 95.513431] ? io_commit_cqring+0x3ec/0x8e0 >> [ 95.514047] __kasan_slab_free+0x141/0x160 >> [ 95.514699] kfree+0xd1/0x390 >> [ 95.515182] io_commit_cqring+0x3ec/0x8e0 >> [ 95.515799] __io_req_complete.part.0+0x64/0x90 >> [ 95.516483] io_wq_submit_work+0x1fa/0x260 >> [ 95.517117] io_worker_handle_work+0xeac/0x1c00 >> [ 95.517828] io_wqe_worker+0xc94/0x11a0 >> [ 95.518438] ? io_worker_handle_work+0x1c00/0x1c00 >> [ 95.519151] ? __kthread_parkme+0x11d/0x1d0 >> [ 95.519806] ? io_worker_handle_work+0x1c00/0x1c00 >> [ 95.520512] ? io_worker_handle_work+0x1c00/0x1c00 >> [ 95.521211] kthread+0x396/0x470 >> [ 95.521727] ? _raw_spin_unlock_irq+0x24/0x30 >> [ 95.522380] ? kthread_mod_delayed_work+0x180/0x180 >> [ 95.523108] ret_from_fork+0x22/0x30 >> [ 95.523684] >> [ 95.523985] Allocated by task 4035: >> [ 95.524543] kasan_save_stack+0x1b/0x40 >> [ 95.525136] __kasan_kmalloc.constprop.0+0xc2/0xd0 >> [ 95.525882] kmem_cache_alloc_trace+0x17b/0x310 >> [ 95.533930] io_queue_sqe+0x225/0xcb0 >> [ 95.534505] io_submit_sqes+0x1768/0x25f0 >> [ 95.535164] __x64_sys_io_uring_enter+0x89e/0xd10 >> [ 95.535900] do_syscall_64+0x33/0x40 >> [ 95.536465] entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> [ 95.537199] >> [ 95.537505] Freed by task 4035: >> [ 95.538003] kasan_save_stack+0x1b/0x40 >> [ 95.538599] kasan_set_track+0x1c/0x30 >> [ 95.539177] kasan_set_free_info+0x1b/0x30 >> [ 95.539798] __kasan_slab_free+0x112/0x160 >> [ 95.540427] kfree+0xd1/0x390 >> [ 95.540910] io_commit_cqring+0x3ec/0x8e0 >> [ 95.541516] io_iopoll_complete+0x914/0x1390 >> [ 95.542150] io_do_iopoll+0x580/0x700 >> [ 95.542724] io_iopoll_try_reap_events.part.0+0x108/0x200 >> [ 95.543512] io_ring_ctx_wait_and_kill+0x118/0x340 >> [ 95.544206] io_uring_release+0x43/0x50 >> [ 95.544791] __fput+0x28d/0x940 >> [ 95.545291] task_work_run+0xea/0x1b0 >> [ 95.545873] do_exit+0xb6a/0x2c60 >> [ 95.546400] do_group_exit+0x12a/0x320 >> [ 95.546967] __x64_sys_exit_group+0x3f/0x50 >> [ 95.547605] do_syscall_64+0x33/0x40 >> [ 95.548155] entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> >> The reason is that once we got a non EAGAIN error in io_wq_submit_work(), >> we'll complete req by calling io_req_complete(), which will hold completion_lock >> to call io_commit_cqring(), but for polled io, io_iopoll_complete() won't >> hold completion_lock to call io_commit_cqring(), then there maybe concurrent >> access to ctx->defer_list, double free may happen. >> >> To fix this bug, we always let io_iopoll_complete() complete polled io. >> >> Reported-by: Abaci Fuzz >> Signed-off-by: Xiaoguang Wang >> --- >> fs/io_uring.c | 15 +++++++++++++-- >> 1 file changed, 13 insertions(+), 2 deletions(-) >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index a8c136a..901ca67 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -6074,8 +6074,19 @@ static struct io_wq_work *io_wq_submit_work(struct io_wq_work *work) >> } >> >> if (ret) { >> - req_set_fail_links(req); >> - io_req_complete(req, ret); >> + /* >> + * io_iopoll_complete() does not hold completion_lock to complete >> + * polled io, so here for polled io, just mark it done and still let >> + * io_iopoll_complete() complete it. >> + */ >> + if (req->ctx->flags & IORING_SETUP_IOPOLL) { >> + struct kiocb *kiocb = &req->rw.kiocb; > > Also remembered that IOPOLL apart from rw can do buf reg/unreg requests, so > it won't work for them. Could you fix it? Sorry for late, I had saw you and jens' discussion in previous mail. I was just busy recently, did't have time to look into this issue. Now I have time to handle it, will have a look at it tomorrow, thanks. Regards, Xiaoguang Wang > >> + >> + kiocb_done(kiocb, ret, NULL); >> + } else { >> + req_set_fail_links(req); >> + io_req_complete(req, ret); >> + } >> } >> >> return io_steal_work(req); >> >