syzbot

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BUG: KCSAN: data-race in n_tty_check_unthrottle / n_tty_receive_buf_common

write to 0xffff88817f1205dc of 4 bytes by task 5774 on cpu 0:
 tty_set_flow_change drivers/tty/tty.h:59 [inline]
 n_tty_check_unthrottle+0xd7/0x1c0 drivers/tty/n_tty.c:280
 n_tty_read+0xf0a/0x11c0 drivers/tty/n_tty.c:2302
 iterate_tty_read drivers/tty/tty_io.c:862 [inline]
 tty_read+0x152/0x470 drivers/tty/tty_io.c:937
 do_iter_readv_writev+0x2b0/0x330
 vfs_readv+0x1e5/0x640 fs/read_write.c:932
 do_readv+0xf8/0x220 fs/read_write.c:994
 __do_sys_readv fs/read_write.c:1085 [inline]
 __se_sys_readv fs/read_write.c:1082 [inline]
 __x64_sys_readv+0x45/0x50 fs/read_write.c:1082
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

write to 0xffff88817f1205dc of 4 bytes by task 5815 on cpu 1:
 n_tty_receive_buf_common+0xadf/0xbc0
 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1775
 tty_ldisc_receive_buf+0x60/0xe0 drivers/tty/tty_buffer.c:386
 paste_selection+0x1dd/0x2e0 drivers/tty/vt/selection.c:409
 tioclinux+0x2c9/0x4a0 drivers/tty/vt/vt.c:3165
 vt_ioctl+0x84e/0x1830 drivers/tty/vt/vt_ioctl.c:762
 tty_ioctl+0x816/0xbc0 drivers/tty/tty_io.c:2803
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000001 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5815 Comm: syz-executor.4 Not tainted 6.8.0-rc2-syzkaller-00031-g861c0981648f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
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