[moderation] [serial?] KCSAN: data-race in __io_arm_poll_handler / __tty_hangup (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1af80d00e1e0 Merge tag 'slab-for-6.16' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17fe9282580000
kernel config: https://syzkaller.appspot.com/x/.config?x=bba874f685309ec0
dashboard link: https://syzkaller.appspot.com/bug?extid=504195d98dd4433f3797
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
CC: [gre...@linuxfoundation.org jiri...@kernel.org linux-...@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/a3e50a712424/disk-1af80d00.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/68bc908308c4/vmlinux-1af80d00.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3d291ba02a2e/bzImage-1af80d00.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+504195...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __io_arm_poll_handler / __tty_hangup

write to 0xffff888125e869c8 of 8 bytes by task 4480 on cpu 1:
__tty_hangup+0x1c2/0x510 drivers/tty/tty_io.c:615
tty_vhangup+0x17/0x20 drivers/tty/tty_io.c:694
pty_close+0x266/0x290 drivers/tty/pty.c:79
tty_release+0x1fc/0xb10 drivers/tty/tty_io.c:1754
__fput+0x29b/0x650 fs/file_table.c:465
____fput+0x1c/0x30 fs/file_table.c:493
task_work_run+0x12e/0x1a0 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xe4/0x100 kernel/entry/common.c:114
exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888125e869c8 of 8 bytes by task 4483 on cpu 0:
vfs_poll include/linux/poll.h:80 [inline]
__io_arm_poll_handler+0x1be/0xb70 io_uring/poll.c:583
io_poll_add+0x69/0xe0 io_uring/poll.c:893
__io_issue_sqe+0xfe/0x2e0 io_uring/io_uring.c:1730
io_issue_sqe+0x53/0x970 io_uring/io_uring.c:1753
io_queue_sqe io_uring/io_uring.c:1960 [inline]
io_submit_sqe io_uring/io_uring.c:2216 [inline]
io_submit_sqes+0x667/0xfd0 io_uring/io_uring.c:2329
__do_sys_io_uring_enter io_uring/io_uring.c:3396 [inline]
__se_sys_io_uring_enter+0x1c1/0x1b70 io_uring/io_uring.c:3330
__x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3330
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+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffffffff8589fd60 -> 0xffffffff8589fc50

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4483 Comm: syz.3.256 Not tainted 6.15.0-syzkaller-11802-g1af80d00e1e0 #0 PREEMPT(voluntary)
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.