syzbot

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BUG: KCSAN: data-race in n_tty_poll / n_tty_set_termios

write to 0xffffc900001dd05d of 1 bytes by task 11196 on cpu 1:
 n_tty_set_termios+0x1fd/0x850 drivers/tty/n_tty.c:1810
 tty_set_termios+0x849/0x8b0 drivers/tty/tty_ioctl.c:352
 set_termios+0x497/0x4e0 drivers/tty/tty_ioctl.c:516
 tty_mode_ioctl+0x391/0x5d0
 n_tty_ioctl_helper+0x8d/0x240 drivers/tty/tty_ioctl.c:986
 n_tty_ioctl+0xfd/0x200 drivers/tty/n_tty.c:2511
 tty_ioctl+0x886/0xbe0 drivers/tty/tty_io.c:2812
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xd3/0x150 fs/ioctl.c:893
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893
 x64_sys_call+0x1581/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffc900001dd05d of 1 bytes by task 11187 on cpu 0:
 input_available_p drivers/tty/n_tty.c:1929 [inline]
 n_tty_poll+0x27c/0x490 drivers/tty/n_tty.c:2458
 tty_poll+0x7e/0x100 drivers/tty/tty_io.c:2214
 vfs_poll include/linux/poll.h:84 [inline]
 do_pollfd fs/select.c:873 [inline]
 do_poll fs/select.c:921 [inline]
 do_sys_poll+0x644/0xc10 fs/select.c:1016
 __do_sys_ppoll fs/select.c:1122 [inline]
 __se_sys_ppoll+0x1af/0x1f0 fs/select.c:1102
 __x64_sys_ppoll+0x67/0x80 fs/select.c:1102
 x64_sys_call+0xeaf/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:272
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x10 -> 0x0c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11187 Comm: syz-executor.1 Tainted: G        W          6.10.0-rc2-syzkaller-00235-g8a92980606e3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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