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

write to 0xffffc90000f39028 of 8 bytes by task 29611 on cpu 0:
 commit_echoes drivers/tty/n_tty.c:767 [inline]
 n_tty_receive_char+0x4be/0x670 drivers/tty/n_tty.c:1419
 n_tty_receive_buf_standard+0x484/0x2d40 drivers/tty/n_tty.c:1588
 __receive_buf drivers/tty/n_tty.c:1612 [inline]
 n_tty_receive_buf_common+0x84c/0xbd0 drivers/tty/n_tty.c:1710
 n_tty_receive_buf2+0x32/0x40 drivers/tty/n_tty.c:1756
 tty_ldisc_receive_buf+0x60/0xe0 drivers/tty/tty_buffer.c:457
 tty_port_default_receive_buf+0x58/0x80 drivers/tty/tty_port.c:39
 receive_buf drivers/tty/tty_buffer.c:515 [inline]
 flush_to_ldisc+0x1ca/0x400 drivers/tty/tty_buffer.c:565
 process_one_work+0x434/0x860 kernel/workqueue.c:2597
 worker_thread+0x5f2/0xa10 kernel/workqueue.c:2748
 kthread+0x1d7/0x210 kernel/kthread.c:389
 ret_from_fork+0x2e/0x40 arch/x86/kernel/process.c:145
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

read to 0xffffc90000f39028 of 8 bytes by task 26551 on cpu 1:
 process_echoes drivers/tty/n_tty.c:793 [inline]
 n_tty_write+0x15c/0xa80 drivers/tty/n_tty.c:2352
 do_tty_write drivers/tty/tty_io.c:1027 [inline]
 file_tty_write+0x396/0x680 drivers/tty/tty_io.c:1098
 tty_write+0x28/0x30 drivers/tty/tty_io.c:1119
 do_iter_write+0x4b4/0x7b0 fs/read_write.c:860
 vfs_iter_write+0x56/0x70 fs/read_write.c:901
 iter_file_splice_write+0x462/0x7e0 fs/splice.c:739
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x8a/0xb0 fs/splice.c:1145
 splice_direct_to_actor+0x31d/0x690 fs/splice.c:1091
 do_splice_direct+0x10d/0x190 fs/splice.c:1197
 do_sendfile+0x3b6/0x9a0 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 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: 0x0000000000000019 -> 0x000000000000002d

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 26551 Comm: syz-executor.4 Not tainted 6.5.0-rc4-syzkaller-00174-gc1a515d3c027 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
==================================================================
__nla_validate_parse: 17 callbacks suppressed
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.4'.