syzbot

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BUG: KCSAN: data-race in n_tty_write / tty_reopen

read-write to 0xffff8881052ef1a8 of 4 bytes by task 31664 on cpu 1:
 tty_reopen+0x10c/0x1b0 drivers/tty/tty_io.c:1373
 tty_open_by_driver drivers/tty/tty_io.c:2084 [inline]
 tty_open+0x8fa/0xb00 drivers/tty/tty_io.c:2137
 chrdev_open+0x34f/0x3c0 fs/char_dev.c:414
 do_dentry_open+0x5cd/0xaf0 fs/open.c:914
 vfs_open+0x4a/0x50 fs/open.c:1048
 do_open fs/namei.c:3636 [inline]
 path_openat+0x17f2/0x1d10 fs/namei.c:3793
 do_filp_open+0xf6/0x200 fs/namei.c:3820
 do_sys_openat2+0xab/0x110 fs/open.c:1407
 do_sys_open fs/open.c:1422 [inline]
 __do_sys_openat fs/open.c:1438 [inline]
 __se_sys_openat fs/open.c:1433 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1433
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881052ef1a8 of 4 bytes by task 31662 on cpu 0:
 n_tty_write+0x316/0xa80 drivers/tty/n_tty.c:2360
 do_tty_write drivers/tty/tty_io.c:1027 [inline]
 file_tty_write+0x396/0x680 drivers/tty/tty_io.c:1098
 tty_write+0x28/0x30 drivers/tty/tty_io.c:1119
 call_write_iter include/linux/fs.h:1871 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4ab/0x7d0 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000001 -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31662 Comm: syz-executor.3 Not tainted 6.5.0-rc3-syzkaller-00283-g12214540ad87 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
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