syzbot

==================================================================
BUG: KCSAN: data-race in n_tty_read / pty_unix98_ioctl

write to 0xffff8881026ca5d9 of 1 bytes by task 19365 on cpu 0:
 pty_unix98_ioctl+0x2a8/0x310 drivers/tty/pty.c:661
 tty_ioctl+0xa8e/0x11a0 drivers/tty/tty_io.c:2805
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:860
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881026ca5d9 of 1 bytes by task 19384 on cpu 1:
 n_tty_read+0x5f4/0x10c0 drivers/tty/n_tty.c:2131
 iterate_tty_read drivers/tty/tty_io.c:868 [inline]
 tty_read+0x199/0x420 drivers/tty/tty_io.c:944
 call_read_iter include/linux/fs.h:2157 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x66c/0x750 fs/read_write.c:485
 ksys_read+0xd9/0x190 fs/read_write.c:623
 __do_sys_read fs/read_write.c:633 [inline]
 __se_sys_read fs/read_write.c:631 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:631
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19384 Comm: syz-executor.3 Not tainted 5.15.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================