syzbot

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BUG: KCSAN: data-race in tty_port_block_til_ready / tty_set_termios

write to 0xffff88813d237110 of 4 bytes by task 7735 on cpu 0:
 tty_set_termios+0x780/0x8a0 drivers/tty/tty_ioctl.c:351
 set_termios+0x47e/0x4c0 drivers/tty/tty_ioctl.c:524
 tty_mode_ioctl+0x3e1/0x590
 n_tty_ioctl_helper+0x8d/0x240 drivers/tty/tty_ioctl.c:992
 n_tty_ioctl+0xfd/0x200 drivers/tty/n_tty.c:2516
 tty_ioctl+0x875/0xbc0 drivers/tty/tty_io.c:2789
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88813d237110 of 4 bytes by task 7731 on cpu 1:
 tty_port_block_til_ready+0x19b/0x4e0 drivers/tty/tty_port.c:548
 tty_port_open+0x1ac/0x1f0 drivers/tty/tty_port.c:792
 uart_open+0x30/0x40 drivers/tty/serial/serial_core.c:1946
 tty_open+0x3d3/0xb00 drivers/tty/tty_io.c:2148
 chrdev_open+0x322/0x390 fs/char_dev.c:414
 do_dentry_open+0x635/0xbd0 fs/open.c:948
 vfs_open+0x4a/0x50 fs/open.c:1082
 do_open fs/namei.c:3622 [inline]
 path_openat+0x1819/0x1d70 fs/namei.c:3779
 do_filp_open+0xf6/0x200 fs/namei.c:3809
 do_sys_openat2+0xab/0x110 fs/open.c:1440
 do_sys_open fs/open.c:1455 [inline]
 __do_sys_openat fs/open.c:1471 [inline]
 __se_sys_openat fs/open.c:1466 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1466
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x02852ed5 -> 0x12832ed5

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7731 Comm: syz-executor.2 Not tainted 6.6.0-syzkaller-03860-g5a6a09e97199 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
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