syzbot

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BUG: KCSAN: data-race in n_tty_write / tty_reopen

write to 0xffff888134fd9da8 of 4 bytes by task 25036 on cpu 0:
 tty_reopen+0x114/0x1c0 drivers/tty/tty_io.c:1368
 tty_open_by_driver drivers/tty/tty_io.c:2080 [inline]
 tty_open+0x8e4/0xb40 drivers/tty/tty_io.c:2133
 chrdev_open+0x362/0x3d0 fs/char_dev.c:414
 do_dentry_open+0x52c/0x860 fs/open.c:824
 vfs_open+0x43/0x50 fs/open.c:959
 do_open fs/namei.c:3476 [inline]
 path_openat+0x170c/0x1f30 fs/namei.c:3609
 do_filp_open+0x105/0x220 fs/namei.c:3636
 do_sys_openat2+0xb5/0x2b0 fs/open.c:1214
 do_sys_open fs/open.c:1230 [inline]
 __do_sys_openat fs/open.c:1246 [inline]
 __se_sys_openat fs/open.c:1241 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1241
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888134fd9da8 of 4 bytes by task 25035 on cpu 1:
 n_tty_write+0x2e8/0xaf0 drivers/tty/n_tty.c:2242
 do_tty_write drivers/tty/tty_io.c:1024 [inline]
 file_tty_write+0x409/0x660 drivers/tty/tty_io.c:1095
 tty_write+0x24/0x30 drivers/tty/tty_io.c:1116
 call_write_iter include/linux/fs.h:2074 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x7f5/0x950 fs/read_write.c:590
 ksys_write+0xd9/0x190 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+0x3e/0x50 fs/read_write.c:652
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000001 -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25035 Comm: syz-executor.5 Not tainted 5.17.0-syzkaller-00192-geaa54b1458ca-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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