syzbot

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BUG: KCSAN: data-race in n_tty_poll / tty_set_termios

write to 0xffff88813ddda51e of 1 bytes by task 25485 on cpu 1:
 unset_locked_termios drivers/tty/tty_ioctl.c:228 [inline]
 tty_set_termios+0x3a4/0x8a0 drivers/tty/tty_ioctl.c:349
 set_termios+0x355/0x4c0 drivers/tty/tty_ioctl.c:528
 tty_mode_ioctl+0x3e1/0x590
 n_tty_ioctl_helper+0x8d/0x240 drivers/tty/tty_ioctl.c:992
 n_tty_ioctl+0xfd/0x200 drivers/tty/n_tty.c:2516
 tty_ioctl+0x875/0xbc0 drivers/tty/tty_io.c:2785
 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:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88813ddda51e of 1 bytes by task 25486 on cpu 0:
 input_available_p drivers/tty/n_tty.c:1932 [inline]
 n_tty_poll+0xbb/0x490 drivers/tty/n_tty.c:2459
 tty_poll+0x7b/0xf0 drivers/tty/tty_io.c:2206
 vfs_poll include/linux/poll.h:88 [inline]
 ep_item_poll fs/eventpoll.c:892 [inline]
 __ep_eventpoll_poll+0x202/0x330 fs/eventpoll.c:861
 ep_eventpoll_poll+0x1f/0x30 fs/eventpoll.c:900
 vfs_poll include/linux/poll.h:88 [inline]
 do_pollfd fs/select.c:873 [inline]
 do_poll fs/select.c:921 [inline]
 do_sys_poll+0x636/0xc00 fs/select.c:1015
 __do_sys_ppoll fs/select.c:1121 [inline]
 __se_sys_ppoll+0x1af/0x1f0 fs/select.c:1101
 __x64_sys_ppoll+0x67/0x80 fs/select.c:1101
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x97 -> 0xd3

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 25486 Comm: syz-executor.5 Not tainted 6.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
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