syzbot

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BUG: KCSAN: data-race in n_tty_ioctl_helper / n_tty_receive_char

write to 0xffff8881365b41bd of 1 bytes by task 4720 on cpu 1:
 n_tty_ioctl_helper+0x2ad/0x340 drivers/tty/tty_ioctl.c:873
 n_tty_ioctl+0xfc/0x1f0 drivers/tty/n_tty.c:2483
 tty_ioctl+0x71e/0x970 drivers/tty/tty_io.c:2787
 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 0xffff8881365b41bd of 1 bytes by task 8 on cpu 0:
 n_tty_receive_char+0x5c/0x6a0 drivers/tty/n_tty.c:1410
 n_tty_receive_buf_standard+0x3b3/0x3a30 drivers/tty/n_tty.c:1589
 __receive_buf drivers/tty/n_tty.c:1613 [inline]
 n_tty_receive_buf_common+0x72d/0xbf0 drivers/tty/n_tty.c:1711
 n_tty_receive_buf2+0x2e/0x40 drivers/tty/n_tty.c:1746
 tty_ldisc_receive_buf+0x5b/0xf0 drivers/tty/tty_buffer.c:457
 tty_port_default_receive_buf+0x54/0x80 drivers/tty/tty_port.c:39
 receive_buf drivers/tty/tty_buffer.c:511 [inline]
 flush_to_ldisc+0x1da/0x480 drivers/tty/tty_buffer.c:561
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8 Comm: kworker/u4:0 Not tainted 6.0.0-rc3-syzkaller-00107-g42e66b1cc3a0-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Workqueue: events_unbound flush_to_ldisc
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