syzbot

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BUG: KCSAN: data-race in __stop_tty / do_con_write

write to 0xffff8881572495bc of 1 bytes by task 24496 on cpu 1:
 __stop_tty+0x42/0x90 drivers/tty/tty_io.c:753
 n_tty_ioctl_helper+0x223/0x240 drivers/tty/tty_ioctl.c:955
 n_tty_ioctl+0xfd/0x200 drivers/tty/n_tty.c:2511
 tty_ioctl+0x886/0xbe0 drivers/tty/tty_io.c:2812
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:904 [inline]
 __se_sys_ioctl+0xd3/0x150 fs/ioctl.c:890
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:890
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

read to 0xffff8881572495bc of 1 bytes by task 24493 on cpu 0:
 do_con_write+0x179/0x3640 drivers/tty/vt/vt.c:2885
 con_write+0x26/0x40 drivers/tty/vt/vt.c:3251
 process_output_block drivers/tty/n_tty.c:574 [inline]
 n_tty_write+0x849/0xb90 drivers/tty/n_tty.c:2379
 iterate_tty_write drivers/tty/tty_io.c:1021 [inline]
 file_tty_write+0x386/0x690 drivers/tty/tty_io.c:1096
 tty_write+0x28/0x30 drivers/tty/tty_io.c:1117
 call_write_iter include/linux/fs.h:2108 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0x771/0x8e0 fs/read_write.c:590
 ksys_write+0xeb/0x1b0 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:652
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 24493 Comm: syz-executor.0 Not tainted 6.8.0-syzkaller-11608-gd95fcdf4961d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
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