[moderation] [serial?] KCSAN: data-race in __tty_hangup / tty_hung_up_p (13)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d69eb204c255 Merge tag 'net-6.17-rc5' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=103c887c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=52ae2e92d7a28724
dashboard link: https://syzkaller.appspot.com/bug?extid=0ddd606c3d58e5663ddd
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
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/71b57e193725/disk-d69eb204.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fe6e375bf647/vmlinux-d69eb204.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e9d043c98cdb/bzImage-d69eb204.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0ddd60...@syzkaller.appspotmail.com

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

write to 0xffff888122eb6308 of 8 bytes by task 14256 on cpu 0:
__tty_hangup+0x1ef/0x540 drivers/tty/tty_io.c:612
tty_vhangup drivers/tty/tty_io.c:691 [inline]
tty_ioctl+0x601/0xb80 drivers/tty/tty_io.c:2732
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xcb/0x140 fs/ioctl.c:584
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:584
x64_sys_call+0x1816/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:17
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

read to 0xffff888122eb6308 of 8 bytes by task 14251 on cpu 1:
tty_hung_up_p+0x20/0x50 drivers/tty/tty_io.c:736
n_tty_poll+0x393/0x450 drivers/tty/n_tty.c:2463
tty_poll+0x79/0xf0 drivers/tty/tty_io.c:2199
vfs_poll include/linux/poll.h:82 [inline]
__io_arm_poll_handler+0x1ee/0xb70 io_uring/poll.c:581
io_arm_apoll+0x3d2/0x4f0 io_uring/poll.c:691
io_arm_poll_handler+0x131/0x160 io_uring/poll.c:720
io_queue_async+0x25b/0x450 io_uring/io_uring.c:2004
io_queue_sqe io_uring/io_uring.c:2032 [inline]
io_submit_sqe io_uring/io_uring.c:2285 [inline]
io_submit_sqes+0xa4d/0x1060 io_uring/io_uring.c:2398
__do_sys_io_uring_enter io_uring/io_uring.c:3465 [inline]
__se_sys_io_uring_enter+0x1c1/0x1b70 io_uring/io_uring.c:3399
__x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3399
x64_sys_call+0x2de1/0x2ff0 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: 0xffffffff858a1f90 -> 0xffffffff858a1e80

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 14251 Comm: syz.4.3765 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================


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