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BUG: KCSAN: data-race in n_tty_poll / tty_set_termios

write to 0xffff88812f75f51f of 1 bytes by task 25463 on cpu 1:
 unset_locked_termios drivers/tty/tty_ioctl.c:236 [inline]
 tty_set_termios+0x41b/0x8b0 drivers/tty/tty_ioctl.c:355
 set_termios+0x384/0x3c0 drivers/tty/tty_ioctl.c:438
 tty_mode_ioctl+0x5ad/0x6a0
 n_tty_ioctl_helper+0x89/0x4c0 drivers/tty/tty_ioctl.c:907
 n_tty_ioctl+0x102/0x200 drivers/tty/n_tty.c:2421
 tty_ioctl+0xaf9/0x11a0 drivers/tty/tty_io.c:2814
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:860
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88812f75f51f of 1 bytes by task 25359 on cpu 0:
 input_available_p drivers/tty/n_tty.c:1868 [inline]
 n_tty_poll+0xee/0x4a0 drivers/tty/n_tty.c:2364
 tty_poll+0xa7/0x140 drivers/tty/tty_io.c:2227
 vfs_poll include/linux/poll.h:90 [inline]
 do_pollfd fs/select.c:869 [inline]
 do_poll fs/select.c:917 [inline]
 do_sys_poll+0x4b8/0xad0 fs/select.c:1011
 __do_sys_ppoll fs/select.c:1117 [inline]
 __se_sys_ppoll+0x18b/0x1d0 fs/select.c:1097
 __x64_sys_ppoll+0x63/0x70 fs/select.c:1097
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x01 -> 0xb9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 25359 Comm: syz-executor.5 Not tainted 5.15.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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