[moderation] [serial?] KCSAN: data-race in __stop_tty / do_con_write (8)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aea6bf908d73 Merge tag 'f2fs-for-6.7-rc1' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17c8d47b680000
kernel config: https://syzkaller.appspot.com/x/.config?x=b1bd7bde690b6f3f
dashboard link: https://syzkaller.appspot.com/bug?extid=2796017df4f6ab824ce1
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/f0d64595ec77/disk-aea6bf90.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/90d60902dcc9/vmlinux-aea6bf90.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7e229fc3c719/bzImage-aea6bf90.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+279601...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __stop_tty / do_con_write

write to 0xffff88815b6fddbc of 1 bytes by task 31334 on cpu 0:
__stop_tty+0x42/0x90 drivers/tty/tty_io.c:753
n_tty_ioctl_helper+0x21f/0x240 drivers/tty/tty_ioctl.c:955
n_tty_ioctl+0xfd/0x200 drivers/tty/n_tty.c:2511
tty_ioctl+0x875/0xbc0 drivers/tty/tty_io.c:2789
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88815b6fddbc of 1 bytes by task 31325 on cpu 1:
do_con_write+0x1459/0x35d0 drivers/tty/vt/vt.c:2885
con_write+0x26/0x40 drivers/tty/vt/vt.c:3251
process_output_block drivers/tty/n_tty.c:574 [inline]
n_tty_write+0x84a/0xb60 drivers/tty/n_tty.c:2379
iterate_tty_write drivers/tty/tty_io.c:1021 [inline]
file_tty_write+0x382/0x680 drivers/tty/tty_io.c:1092
tty_write+0x28/0x30 drivers/tty/tty_io.c:1113
call_write_iter include/linux/fs.h:2020 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x48a/0x790 fs/read_write.c:584
ksys_write+0xeb/0x1a0 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:646
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 31325 Comm: syz-executor.3 Not tainted 6.6.0-syzkaller-14263-gaea6bf908d73 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

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