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BUG: KCSAN: data-race in n_tty_write / tty_set_termios

read-write to 0xffff8881330a4d14 of 4 bytes by task 10874 on cpu 0:
 unset_locked_termios drivers/tty/tty_ioctl.c:233 [inline]
 tty_set_termios+0x1b4/0x890 drivers/tty/tty_ioctl.c:355
 set_termios+0x388/0x3c0 drivers/tty/tty_ioctl.c:438
 tty_mode_ioctl+0x4fa/0x5d0
 n_tty_ioctl_helper+0x83/0x340 drivers/tty/tty_ioctl.c:903
 n_tty_ioctl+0xfc/0x1f0 drivers/tty/n_tty.c:2381
 tty_ioctl+0x71e/0x970 drivers/tty/tty_io.c:2787
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:856
 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+0x46/0xb0

read to 0xffff8881330a4d14 of 4 bytes by task 10867 on cpu 1:
 n_tty_write+0x88/0xb40 drivers/tty/n_tty.c:2225
 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:2060 [inline]
 new_sync_write fs/read_write.c:504 [inline]
 vfs_write+0x71c/0x890 fs/read_write.c:591
 ksys_write+0xe8/0x1a0 fs/read_write.c:644
 __do_sys_write fs/read_write.c:656 [inline]
 __se_sys_write fs/read_write.c:653 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:653
 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+0x46/0xb0

value changed: 0x0000ffff -> 0x00010001

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10867 Comm: syz-executor.4 Not tainted 5.18.0-syzkaller-11538-ge1cbc3b96a99-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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