syzbot

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BUG: KCSAN: data-race in __stop_tty / do_con_write

write to 0xffff88813800adbc of 1 bytes by task 17783 on cpu 1:
 __stop_tty+0x3e/0x80 drivers/tty/tty_io.c:760
 n_tty_ioctl_helper+0x2bd/0x340 drivers/tty/tty_ioctl.c:874
 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 0xffff88813800adbc of 1 bytes by task 17782 on cpu 0:
 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:586 [inline]
 n_tty_write+0x809/0xb10 drivers/tty/n_tty.c:2350
 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:2187 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x468/0x760 fs/read_write.c:578
 ksys_write+0xe8/0x1a0 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 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

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17782 Comm: syz-executor.3 Not tainted 6.0.0-rc6-syzkaller-00210-gbf682942cd26-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
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