syzbot

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BUG: KCSAN: data-race in n_tty_poll / tty_set_termios

read-write to 0xffff8881186f4d14 of 4 bytes by task 3772 on cpu 1:
 unset_locked_termios drivers/tty/tty_ioctl.c:217 [inline]
 tty_set_termios+0x1a2/0x8b0 drivers/tty/tty_ioctl.c:340
 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:2521
 tty_ioctl+0x87a/0xbe0 drivers/tty/tty_io.c:2811
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xc9/0x140 fs/ioctl.c:892
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892
 x64_sys_call+0x1690/0x2dc0 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 0xffff8881186f4d14 of 4 bytes by task 3767 on cpu 0:
 input_available_p drivers/tty/n_tty.c:1939 [inline]
 n_tty_poll+0x2b9/0x4b0 drivers/tty/n_tty.c:2468
 tty_poll+0x78/0xf0 drivers/tty/tty_io.c:2208
 vfs_poll include/linux/poll.h:82 [inline]
 __io_arm_poll_handler+0x1e5/0xd50 io_uring/poll.c:582
 io_poll_add+0x6b/0xf0 io_uring/poll.c:892
 io_issue_sqe+0x15f/0xb70 io_uring/io_uring.c:1737
 io_queue_sqe io_uring/io_uring.c:1947 [inline]
 io_submit_sqe io_uring/io_uring.c:2204 [inline]
 io_submit_sqes+0x680/0x1070 io_uring/io_uring.c:2321
 __do_sys_io_uring_enter io_uring/io_uring.c:3372 [inline]
 __se_sys_io_uring_enter+0x1c0/0x1b00 io_uring/io_uring.c:3307
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3307
 x64_sys_call+0xb5e/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:427
 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: 0x00008a3b -> 0x00000fff

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3767 Comm: syz.4.9761 Not tainted 6.14.0-rc7-syzkaller-00202-g183601b78a9b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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