[moderation] [io-uring?] KCSAN: data-race in __io_queue_proc / io_poll_wake (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 94305e83eccb Merge tag 'pmdomain-v6.15-rc3' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17034170580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ea93cce608593e25
dashboard link: https://syzkaller.appspot.com/bug?extid=638b9d32d0daeb73cdb0
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
CC: [asml.s...@gmail.com ax...@kernel.dk io-u...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2e2086a524bb/disk-94305e83.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1a787d9f7032/vmlinux-94305e83.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5544ad89b0c2/bzImage-94305e83.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+638b9d...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __io_queue_proc / io_poll_wake

write to 0xffff88812f7827e8 of 8 bytes by task 1460 on cpu 1:
io_poll_wake+0x1f9/0x3b0 io_uring/poll.c:420
__wake_up_common kernel/sched/wait.c:89 [inline]
__wake_up_common_lock kernel/sched/wait.c:106 [inline]
__wake_up+0x66/0xb0 kernel/sched/wait.c:127
n_tty_receive_handle_newline drivers/tty/n_tty.c:1250 [inline]
n_tty_receive_char_canon drivers/tty/n_tty.c:1306 [inline]
n_tty_receive_char_special drivers/tty/n_tty.c:1372 [inline]
n_tty_receive_buf_standard+0x2011/0x2f10 drivers/tty/n_tty.c:1588
__receive_buf drivers/tty/n_tty.c:1624 [inline]
n_tty_receive_buf_common+0x805/0xbe0 drivers/tty/n_tty.c:1723
n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1763
tiocsti+0x170/0x1d0 drivers/tty/tty_io.c:2299
tty_ioctl+0x4a4/0xb80 drivers/tty/tty_io.c:2716
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xcb/0x140 fs/ioctl.c:892
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892
x64_sys_call+0x19a8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88812f7827e8 of 8 bytes by task 1451 on cpu 0:
__io_queue_proc+0x10a/0x280 io_uring/poll.c:473
io_async_queue_proc+0x43/0x50 io_uring/poll.c:636
poll_wait include/linux/poll.h:45 [inline]
n_tty_poll+0x7a/0x450 drivers/tty/n_tty.c:2451
tty_poll+0x79/0xf0 drivers/tty/tty_io.c:2208
vfs_poll include/linux/poll.h:82 [inline]
__io_arm_poll_handler+0x1ee/0xb70 io_uring/poll.c:583
io_arm_poll_handler+0x427/0x5b0 io_uring/poll.c:708
io_queue_async+0x60/0x3e0 io_uring/io_uring.c:1945
io_queue_sqe io_uring/io_uring.c:1971 [inline]
io_submit_sqe io_uring/io_uring.c:2220 [inline]
io_submit_sqes+0xa0c/0x1000 io_uring/io_uring.c:2337
__do_sys_io_uring_enter io_uring/io_uring.c:3397 [inline]
__se_sys_io_uring_enter+0x1c1/0x1b70 io_uring/io_uring.c:3331
__x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3331
x64_sys_call+0x28c8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:427
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88811660ea08 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 1451 Comm: syz.8.18997 Tainted: G W 6.15.0-rc7-syzkaller-00099-g94305e83eccb #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.