syzbot

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BUG: KCSAN: data-race in __tty_hangup / n_tty_poll

write to 0xffff888115226dd4 of 1 bytes by task 4559 on cpu 0:
 __tty_hangup+0x427/0x540 drivers/tty/tty_io.c:639
 tty_vhangup drivers/tty/tty_io.c:700 [inline]
 tty_ioctl+0x613/0xbe0 drivers/tty/tty_io.c:2743
 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+0x15cc/0x2d60 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 0xffff888115226dd4 of 1 bytes by task 4558 on cpu 1:
 n_tty_poll+0x392/0x490 drivers/tty/n_tty.c:2471
 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+0xe71/0x2d60 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: 0x03 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4558 Comm: syz.3.275 Not tainted 6.11.0-rc6-syzkaller-00026-g88fac17500f4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
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