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BUG: KCSAN: data-race in n_tty_receive_char / n_tty_write

write to 0xffffc90000df5028 of 8 bytes by task 8 on cpu 1:
 commit_echoes drivers/tty/n_tty.c:768 [inline]
 n_tty_receive_char+0x4d0/0x6a0 drivers/tty/n_tty.c:1420
 n_tty_receive_buf_standard+0x3b3/0x3a30 drivers/tty/n_tty.c:1589
 __receive_buf drivers/tty/n_tty.c:1613 [inline]
 n_tty_receive_buf_common+0x72d/0xbf0 drivers/tty/n_tty.c:1711
 n_tty_receive_buf2+0x2e/0x40 drivers/tty/n_tty.c:1746
 tty_ldisc_receive_buf+0x5b/0xf0 drivers/tty/tty_buffer.c:457
 tty_port_default_receive_buf+0x54/0x80 drivers/tty/tty_port.c:39
 receive_buf drivers/tty/tty_buffer.c:515 [inline]
 flush_to_ldisc+0x1d9/0x470 drivers/tty/tty_buffer.c:565
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

read to 0xffffc90000df5028 of 8 bytes by task 15943 on cpu 0:
 process_echoes drivers/tty/n_tty.c:794 [inline]
 n_tty_write+0x13e/0xb10 drivers/tty/n_tty.c:2336
 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: 0x000000000000007f -> 0x0000000000000089

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15943 Comm: syz-executor.1 Not tainted 6.0.0-rc7-syzkaller-00042-g46452d3786a8-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
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