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 3DF0FC77B61 for ; Mon, 24 Apr 2023 07:37:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230500AbjDXHhl (ORCPT ); Mon, 24 Apr 2023 03:37:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230476AbjDXHhk (ORCPT ); Mon, 24 Apr 2023 03:37:40 -0400 Received: from mail-lf1-x12f.google.com (mail-lf1-x12f.google.com [IPv6:2a00:1450:4864:20::12f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB04DE5E for ; Mon, 24 Apr 2023 00:37:38 -0700 (PDT) Received: by mail-lf1-x12f.google.com with SMTP id 2adb3069b0e04-4efea87c578so2131e87.1 for ; Mon, 24 Apr 2023 00:37:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1682321857; x=1684913857; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=8vPDN1IVpdxIsn0EC3yloIXo6DGRLNTlpDHTNR3qIwE=; b=O+uUN6Nt/f5/IC46DSvy8JpHPyZScu1zJV+qIJlrDLmEOMJTOjYSyGMkE3c3TwaEma wRphiMjCvKV1Tj8HCmXWuRpElf/VxaRIWsulypBEFA9bqFfyWMvMke7/YcwT1BdYoM0U FXAIKjiV/LI5rwBjGueYRbWJFF8u6kLr+/B8NdmINHjSn49qQeJBsw8QOpXpQOMPqX1M TQ3xeGplBZ3VGZXa6L6zh7wAVl1IFeOzDGi0IZdvsIqzuwF+4ZdxLSNNSj23SzZpP118 fKvPucpSglRlSWO4nZe4aHv7s3r9Rd+aH2/igEzAp9XcguDGFyiWbRjfp/lkonoROd5f IhLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682321857; x=1684913857; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=8vPDN1IVpdxIsn0EC3yloIXo6DGRLNTlpDHTNR3qIwE=; b=Pbwk0tOESg+TjKyskskQQ2tv4ae5pCaDEN67SzlEmypxzFBI43uLogbeLs3WUIEuk6 xIKVdLhy0eX0Icz2dP6NwtY2evjNttutQSVGHsR0M/dE8Tt8u+9pkd9eawXapJ/0qEfH VXUCyg7kdXK+WLLkzW/Jt7mjeXi6pijG7bQHC6NigEvb8fO6dQ/fXyPqxPis0ZJogFsh aFStdFIwTCIrRqm/ZirMYjPup2iY9ji/MOTT2s+AEy2tZVqifoiohWDVOL5WnceHOWcY /G0wjfWf6yjNlNaDH4y8BRm/v4+Oorc+KaV/4oRhgqG7o5zZ6jj/YlmKVehdGbVA9wOm zssw== X-Gm-Message-State: AAQBX9eS0AbI8NNUIAA4UfMKPVwqHkgVMkQZl/BbWfOF6pwIavXDXC8r SMkILEUGHXaKANLrcS3I18sWekXjKbkYXFNUIXJmbA== X-Google-Smtp-Source: AKy350b3s1yTa7+Lmwcx2UhoZh5NZ1X+UfVTd2wT5LZJZ6DKEuGma1DWJkWhS/FE0tmnAWcK7ep6o8WUpPuJl2gqEvI= X-Received: by 2002:a05:6512:3e23:b0:4d0:e0ee:fc70 with SMTP id i35-20020a0565123e2300b004d0e0eefc70mr203824lfv.0.1682321856802; Mon, 24 Apr 2023 00:37:36 -0700 (PDT) MIME-Version: 1.0 References: <000000000000d7848305fa0fd413@google.com> In-Reply-To: <000000000000d7848305fa0fd413@google.com> From: Dmitry Vyukov Date: Mon, 24 Apr 2023 09:37:23 +0200 Message-ID: Subject: Re: [syzbot] [io-uring?] KCSAN: data-race in __io_fill_cqe_req / io_timeout To: syzbot Cc: asml.silence@gmail.com, axboe@kernel.dk, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Mon, 24 Apr 2023 at 09:19, syzbot wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: 3a93e40326c8 Merge tag 'for-linus' of git://git.kernel.org.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1280071ec80000 > kernel config: https://syzkaller.appspot.com/x/.config?x=f7350c77b8056a38 > dashboard link: https://syzkaller.appspot.com/bug?extid=cb265db2f3f3468ef436 > compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/2122926bc9fe/disk-3a93e403.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/8392992358bc/vmlinux-3a93e403.xz > kernel image: https://storage.googleapis.com/syzbot-assets/6398a2d19a7e/bzImage-3a93e403.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+cb265db2f3f3468ef436@syzkaller.appspotmail.com I did not fully grasp what happens here, but it looks suspicious. The comment in io_timeout() says that it computes "events that need to occur for this timeout event to be satisfied". But if the range is racing, it marks a random set of events? > ================================================================== > BUG: KCSAN: data-race in __io_fill_cqe_req / io_timeout > > read-write to 0xffff888108bf8310 of 4 bytes by task 20447 on cpu 0: > io_get_cqe_overflow io_uring/io_uring.h:112 [inline] > io_get_cqe io_uring/io_uring.h:124 [inline] > __io_fill_cqe_req+0x6c/0x4d0 io_uring/io_uring.h:137 > io_fill_cqe_req io_uring/io_uring.h:165 [inline] > __io_req_complete_post+0x67/0x790 io_uring/io_uring.c:969 > io_req_complete_post io_uring/io_uring.c:1006 [inline] > io_req_task_complete+0xb9/0x110 io_uring/io_uring.c:1654 > handle_tw_list io_uring/io_uring.c:1184 [inline] > tctx_task_work+0x1fe/0x4d0 io_uring/io_uring.c:1246 > task_work_run+0x123/0x160 kernel/task_work.c:179 > get_signal+0xe5c/0xfe0 kernel/signal.c:2635 > arch_do_signal_or_restart+0x89/0x2b0 arch/x86/kernel/signal.c:306 > exit_to_user_mode_loop+0x6d/0xe0 kernel/entry/common.c:168 > exit_to_user_mode_prepare+0x6a/0xa0 kernel/entry/common.c:204 > __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] > syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:297 > do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > read to 0xffff888108bf8310 of 4 bytes by task 20448 on cpu 1: > io_timeout+0x88/0x270 io_uring/timeout.c:546 > io_issue_sqe+0x147/0x660 io_uring/io_uring.c:1907 > io_queue_sqe io_uring/io_uring.c:2079 [inline] > io_submit_sqe io_uring/io_uring.c:2340 [inline] > io_submit_sqes+0x689/0xfe0 io_uring/io_uring.c:2450 > __do_sys_io_uring_enter io_uring/io_uring.c:3458 [inline] > __se_sys_io_uring_enter+0x1e5/0x1b70 io_uring/io_uring.c:3392 > __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3392 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > value changed: 0x00000c75 -> 0x00000c76 > > Reported by Kernel Concurrency Sanitizer on: > CPU: 1 PID: 20448 Comm: syz-executor.2 Not tainted 6.3.0-rc4-syzkaller-00025-g3a93e40326c8 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 > ================================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000d7848305fa0fd413%40google.com.