syzbot

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BUG: KCSAN: data-race in __se_sys_ioctl / __tty_hangup

write to 0xffff8881389e9628 of 8 bytes by task 30700 on cpu 1:
 __tty_hangup+0x247/0x650 drivers/tty/tty_io.c:630
 tty_vhangup+0x13/0x20 drivers/tty/tty_io.c:711
 pty_close+0x27b/0x2a0 drivers/tty/pty.c:79
 tty_release+0x255/0xa10 drivers/tty/tty_io.c:1771
 __fput+0x25b/0x4e0 fs/file_table.c:280
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0xae/0x130 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
 exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
 do_syscall_64+0x49/0x90 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881389e9628 of 8 bytes by task 30709 on cpu 0:
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xa5/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffffffff8308e898 -> 0xffffffff8308e798

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 30709 Comm: syz-executor.2 Not tainted 5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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