syzbot

==================================================================
BUG: KCSAN: data-race in n_tty_poll / tty_set_termios

write to 0xffff888117895508 of 44 bytes by task 8178 on cpu 1:
 tty_set_termios+0xc0/0x8c0 drivers/tty/tty_ioctl.c:339
 set_termios+0x496/0x4e0 drivers/tty/tty_ioctl.c:516
 tty_mode_ioctl+0x379/0x5c0 drivers/tty/tty_ioctl.c:-1
 n_tty_ioctl_helper+0x91/0x210 drivers/tty/tty_ioctl.c:986
 n_tty_ioctl+0x101/0x200 drivers/tty/n_tty.c:2509
 tty_ioctl+0x842/0xb80 drivers/tty/tty_io.c:2811
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:892
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892
 x64_sys_call+0x19a8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811789551f of 1 bytes by task 8175 on cpu 0:
 input_available_p drivers/tty/n_tty.c:1921 [inline]
 n_tty_poll+0xec/0x450 drivers/tty/n_tty.c:2452
 tty_poll+0x79/0xf0 drivers/tty/tty_io.c:2208
 vfs_poll include/linux/poll.h:82 [inline]
 io_file_supports_nowait io_uring/rw.c:46 [inline]
 __io_read+0x2e7/0xc10 io_uring/rw.c:923
 io_read+0x1c/0x60 io_uring/rw.c:1016
 __io_issue_sqe+0xfb/0x2e0 io_uring/io_uring.c:1734
 io_issue_sqe+0x53/0x970 io_uring/io_uring.c:1757
 io_queue_sqe io_uring/io_uring.c:1963 [inline]
 io_submit_sqe io_uring/io_uring.c:2219 [inline]
 io_submit_sqes+0x64c/0x1000 io_uring/io_uring.c:2336
 __do_sys_io_uring_enter io_uring/io_uring.c:3396 [inline]
 __se_sys_io_uring_enter+0x1c1/0x1b70 io_uring/io_uring.c:3330
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3330
 x64_sys_call+0x28c8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x01 -> 0xb7

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 8175 Comm: syz.6.1791 Not tainted 6.15.0-rc6-syzkaller-00188-gfee3e843b309 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
==================================================================