==================================================================
BUG: KCSAN: data-race in __stop_tty / n_tty_receive_char

write to 0xffff8881187995bc of 1 bytes by task 9203 on cpu 1:
 __stop_tty+0x42/0x90 drivers/tty/tty_io.c:747
 n_tty_ioctl_helper+0x223/0x240 drivers/tty/tty_ioctl.c:955
 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 0xffff8881187995bc of 1 bytes by task 153 on cpu 0:
 n_tty_receive_char+0x3d/0x680 drivers/tty/n_tty.c:1427
 n_tty_receive_buf_standard+0x4bd/0x2e30 drivers/tty/n_tty.c:1606
 __receive_buf drivers/tty/n_tty.c:1640 [inline]
 n_tty_receive_buf_common+0x830/0xbd0 drivers/tty/n_tty.c:1739
 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1785
 tty_ldisc_receive_buf+0x63/0x100 drivers/tty/tty_buffer.c:387
 tty_port_default_receive_buf+0x59/0x90 drivers/tty/tty_port.c:37
 receive_buf drivers/tty/tty_buffer.c:445 [inline]
 flush_to_ldisc+0x1ce/0x410 drivers/tty/tty_buffer.c:495
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4db/0xa20 kernel/workqueue.c:3319
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3400
 kthread+0x4ae/0x520 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 153 Comm: kworker/u8:5 Tainted: G        W          6.14.0-rc4-syzkaller-00295-gb91872c56940 #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: events_unbound flush_to_ldisc
==================================================================
net_ratelimit: 30 callbacks suppressed
batman_adv: batadv0: Local translation table size (60) exceeds maximum packet size (-320); Ignoring new local tt entry: 33:33:00:00:00:01
batman_adv: batadv0: Local translation table size (60) exceeds maximum packet size (-320); Ignoring new local tt entry: 33:33:ff:00:00:2a
batman_adv: batadv0: Local translation table size (60) exceeds maximum packet size (-320); Ignoring new local tt entry: 33:33:ff:aa:aa:2a
batman_adv: batadv0: Local translation table size (60) exceeds maximum packet size (-320); Ignoring new local tt entry: 01:00:5e:00:00:01
batman_adv: batadv0: Local translation table size (60) exceeds maximum packet size (-320); Ignoring new local tt entry: 33:33:00:00:00:01
batman_adv: batadv0: Local translation table size (60) exceeds maximum packet size (-320); Ignoring new local tt entry: 33:33:ff:00:00:2a
net_ratelimit: 30 callbacks suppressed
batman_adv: batadv0: Local translation table size (60) exceeds maximum packet size (-320); Ignoring new local tt entry: 33:33:00:00:00:01
batman_adv: batadv0: Local translation table size (60) exceeds maximum packet size (-320); Ignoring new local tt entry: 33:33:ff:00:00:2a
batman_adv: batadv0: Local translation table size (60) exceeds maximum packet size (-320); Ignoring new local tt entry: 33:33:ff:aa:aa:2a
batman_adv: batadv0: Local translation table size (60) exceeds maximum packet size (-320); Ignoring new local tt entry: 01:00:5e:00:00:01