[moderation] [serial?] KCSAN: data-race in __tty_hangup / tty_hung_up_p (12)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bf9aa14fc523 Merge tag 'timers-core-2024-11-18' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=142246c0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a4239a0e02e161ec
dashboard link: https://syzkaller.appspot.com/bug?extid=3fa209762cb8e7d2e8ce
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
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/5889d7019bad/disk-bf9aa14f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8d0c07d02151/vmlinux-bf9aa14f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bafa60632b80/bzImage-bf9aa14f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3fa209...@syzkaller.appspotmail.com

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

write to 0xffff888115c6d310 of 8 bytes by task 4475 on cpu 1:
__tty_hangup+0x1d6/0x530 drivers/tty/tty_io.c:615
tty_vhangup+0x17/0x20 drivers/tty/tty_io.c:694
pty_close+0x262/0x280 drivers/tty/pty.c:79
tty_release+0x206/0x930 drivers/tty/tty_io.c:1754
__fput+0x17a/0x6d0 fs/file_table.c:450
____fput+0x1c/0x30 fs/file_table.c:478
task_work_run+0x13a/0x1a0 kernel/task_work.c:239
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0xa8/0x120 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888115c6d310 of 8 bytes by task 4468 on cpu 0:
tty_hung_up_p+0x20/0x50 drivers/tty/tty_io.c:739
n_tty_write+0x2e7/0xb80 drivers/tty/n_tty.c:2383
iterate_tty_write drivers/tty/tty_io.c:1015 [inline]
file_tty_write+0x37a/0x680 drivers/tty/tty_io.c:1090
tty_write+0x28/0x30 drivers/tty/tty_io.c:1111
new_sync_write fs/read_write.c:586 [inline]
vfs_write+0x77f/0x920 fs/read_write.c:679
ksys_write+0xe8/0x1b0 fs/read_write.c:731
__do_sys_write fs/read_write.c:742 [inline]
__se_sys_write fs/read_write.c:739 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:739
x64_sys_call+0x287e/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffffffff8569cef8 -> 0xffffffff8569cd90

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4468 Comm: syz.4.354 Tainted: G W 6.12.0-syzkaller-01782-gbf9aa14fc523 #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
==================================================================


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[syzbot]

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