syzbot

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BUG: KCSAN: data-race in __stop_tty / do_con_write

write to 0xffff88813047edbc of 1 bytes by task 9964 on cpu 1:
 __stop_tty+0x3e/0x80 drivers/tty/tty_io.c:768
 n_tty_ioctl_helper+0x317/0x450 drivers/tty/tty_ioctl.c:876
 n_tty_ioctl+0x102/0x200 drivers/tty/n_tty.c:2421
 tty_ioctl+0xaf5/0x1130 drivers/tty/tty_io.c:2814
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:860
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813047edbc of 1 bytes by task 9956 on cpu 0:
 do_con_write+0x2055/0x5f40 drivers/tty/vt/vt.c:2931
 con_write+0x20/0x40 drivers/tty/vt/vt.c:3295
 n_tty_write+0x39b/0xaf0 drivers/tty/n_tty.c:2311
 do_tty_write drivers/tty/tty_io.c:1038 [inline]
 file_tty_write+0x409/0x660 drivers/tty/tty_io.c:1110
 tty_write+0x24/0x30 drivers/tty/tty_io.c:1131
 call_write_iter include/linux/fs.h:2161 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:725
 do_iter_write+0x192/0x5c0 fs/read_write.c:851
 vfs_writev fs/read_write.c:924 [inline]
 do_writev+0x250/0x4d0 fs/read_write.c:967
 __do_sys_writev fs/read_write.c:1040 [inline]
 __se_sys_writev fs/read_write.c:1037 [inline]
 __x64_sys_writev+0x41/0x50 fs/read_write.c:1037
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9956 Comm: syz-executor.4 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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