syzbot

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BUG: KCSAN: data-race in tty_port_block_til_ready / tty_set_termios

write to 0xffff888138aa9510 of 4 bytes by task 20569 on cpu 1:
 tty_set_termios+0x780/0x8a0 drivers/tty/tty_ioctl.c:360
 set_termios+0x241/0x270 drivers/tty/tty_ioctl.c:517
 tty_mode_ioctl+0x3e1/0x580
 n_tty_ioctl_helper+0x8d/0x240 drivers/tty/tty_ioctl.c:980
 n_tty_ioctl+0xfd/0x200 drivers/tty/n_tty.c:2483
 tty_ioctl+0x86f/0xbc0 drivers/tty/tty_io.c:2786
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xc9/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888138aa9510 of 4 bytes by task 20572 on cpu 0:
 tty_port_block_til_ready+0xe9/0x4e0 drivers/tty/tty_port.c:532
 tty_port_open+0x1ac/0x1f0 drivers/tty/tty_port.c:794
 uart_open+0x30/0x40 drivers/tty/serial/serial_core.c:1925
 tty_open+0x3d0/0xb00 drivers/tty/tty_io.c:2145
 chrdev_open+0x349/0x3c0 fs/char_dev.c:414
 do_dentry_open+0x5b3/0x930 fs/open.c:920
 vfs_open+0x47/0x50 fs/open.c:1051
 do_open fs/namei.c:3560 [inline]
 path_openat+0x17e6/0x1d00 fs/namei.c:3715
 do_filp_open+0xf6/0x200 fs/namei.c:3742
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1348
 do_sys_open fs/open.c:1364 [inline]
 __do_sys_openat fs/open.c:1380 [inline]
 __se_sys_openat fs/open.c:1375 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1375
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000013 -> 0x000000e6

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 20572 Comm: syz-executor.1 Not tainted 6.3.0-rc7-syzkaller-00136-g6a66fdd29ea1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
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