syzbot

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BUG: KCSAN: data-race in do_con_write / stop_tty

write to 0xffff888137f7fdbc of 1 bytes by task 3358 on cpu 0:
 __stop_tty drivers/tty/tty_io.c:760 [inline]
 stop_tty+0x54/0xb0 drivers/tty/tty_io.c:784
 n_tty_receive_char_special drivers/tty/n_tty.c:1234 [inline]
 n_tty_receive_buf_standard drivers/tty/n_tty.c:1530 [inline]
 __receive_buf drivers/tty/n_tty.c:1549 [inline]
 n_tty_receive_buf_common+0x10fd/0x4c40 drivers/tty/n_tty.c:1645
 n_tty_receive_buf+0x2b/0x40 drivers/tty/n_tty.c:1674
 tiocsti+0x14b/0x1a0 drivers/tty/tty_io.c:2293
 tty_ioctl+0x279/0x970 drivers/tty/tty_io.c:2692
 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+0x44/0xae

read to 0xffff888137f7fdbc of 1 bytes by task 3352 on cpu 1:
 do_con_write+0x1785/0x3590 drivers/tty/vt/vt.c:2931
 con_write+0x25/0x420 drivers/tty/vt/vt.c:3295
 process_output_block drivers/tty/n_tty.c:581 [inline]
 n_tty_write+0x7ea/0xb40 drivers/tty/n_tty.c:2248
 do_tty_write drivers/tty/tty_io.c:1024 [inline]
 file_tty_write+0x3f9/0x650 drivers/tty/tty_io.c:1095
 tty_write+0x24/0x30 drivers/tty/tty_io.c:1116
 call_write_iter include/linux/fs.h:2050 [inline]
 new_sync_write fs/read_write.c:504 [inline]
 vfs_write+0x71c/0x890 fs/read_write.c:591
 ksys_write+0xe8/0x1a0 fs/read_write.c:644
 __do_sys_write fs/read_write.c:656 [inline]
 __se_sys_write fs/read_write.c:653 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:653
 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+0x44/0xae

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3352 Comm: syz-executor.1 Not tainted 5.18.0-rc1-syzkaller-00350-g1862a69c9174-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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