syzbot

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BUG: KCSAN: data-race in __stop_tty / do_con_write

write to 0xffff88816e51ddbc of 1 bytes by task 10879 on cpu 0:
 __stop_tty+0x42/0x90 drivers/tty/tty_io.c:754
 n_tty_ioctl_helper+0x21f/0x240 drivers/tty/tty_ioctl.c:971
 n_tty_ioctl+0xfd/0x200 drivers/tty/n_tty.c:2482
 tty_ioctl+0x86f/0xbc0 drivers/tty/tty_io.c:2786
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xc9/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88816e51ddbc of 1 bytes by task 10869 on cpu 1:
 do_con_write+0x1459/0x35d0 drivers/tty/vt/vt.c:2886
 con_write+0x24/0x40 drivers/tty/vt/vt.c:3246
 n_tty_write+0x3b3/0xa80 drivers/tty/n_tty.c:2372
 do_tty_write drivers/tty/tty_io.c:1018 [inline]
 file_tty_write+0x3a0/0x600 drivers/tty/tty_io.c:1089
 tty_write+0x28/0x30 drivers/tty/tty_io.c:1110
 call_write_iter include/linux/fs.h:1868 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x47b/0x780 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:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10869 Comm: syz-executor.2 Not tainted 6.4.0-rc6-syzkaller-00037-gb6dad5178cea #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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