syzbot

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BUG: KCSAN: data-race in __stop_tty / tty_send_xchar

write to 0xffff8881074f2dbc of 1 bytes by task 16407 on cpu 1:
 __stop_tty+0x3e/0x80 drivers/tty/tty_io.c:754
 n_tty_ioctl_helper+0x2bd/0x340 drivers/tty/tty_ioctl.c:949
 n_tty_ioctl+0xfc/0x1f0 drivers/tty/n_tty.c:2483
 tty_ioctl+0x6e9/0x940 drivers/tty/tty_io.c:2784
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881074f2dbc of 1 bytes by task 16410 on cpu 0:
 tty_send_xchar+0x45/0x280 drivers/tty/tty_io.c:1147
 n_tty_ioctl_helper+0x288/0x340
 n_tty_ioctl+0xfc/0x1f0 drivers/tty/n_tty.c:2483
 tty_ioctl+0x6e9/0x940 drivers/tty/tty_io.c:2784
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16410 Comm: syz-executor.3 Tainted: G        W          6.2.0-rc1-syzkaller-00095-ge4cf7c25bae5-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
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