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Date:   Mon, 24 Apr 2023 00:19:45 -0700
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Subject: [syzbot] [io-uring?] KCSAN: data-race in __io_fill_cqe_req / io_timeout
From:   syzbot <syzbot+cb265db2f3f3468ef436@syzkaller.appspotmail.com>
To:     asml.silence@gmail.com, axboe@kernel.dk, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
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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

==================================================================
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
==================================================================


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