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BUG: KCSAN: data-race in n_tty_receive_char_inline / n_tty_receive_char_special

write to 0xffffc900179e1018 of 8 bytes by task 3132 on cpu 1:
 add_echo_byte syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:846 [inline]
 echo_char syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:949 [inline]
 n_tty_receive_char_special+0x1fd9/0x3ac0 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:1394
 n_tty_receive_buf_standard syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:1585 [inline]
 __receive_buf syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:1647 [inline]
 n_tty_receive_buf_common+0x191c/0x1e20 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:1744
 n_tty_receive_buf+0x2b/0x40 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:1773
 tiocsti syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/tty_io.c:2211 [inline]
 tty_ioctl+0x91a/0x10c0 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/tty_io.c:2591
 vfs_ioctl syzkaller/managers/upstream-kcsan-gce/kernel/fs/ioctl.c:48 [inline]
 __do_sys_ioctl syzkaller/managers/upstream-kcsan-gce/kernel/fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xcb/0x140 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ioctl.c:739
 __x64_sys_ioctl+0x3f/0x50 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ioctl.c:739
 do_syscall_64+0x39/0x80 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffc900179e1018 of 8 bytes by task 4450 on cpu 0:
 commit_echoes syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:780 [inline]
 n_tty_receive_char_inline+0x4cb/0x680 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:1422
 n_tty_receive_buf_standard syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:1584 [inline]
 __receive_buf syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:1647 [inline]
 n_tty_receive_buf_common+0x1893/0x1e20 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:1744
 n_tty_receive_buf2+0x2e/0x40 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/n_tty.c:1779
 tty_ldisc_receive_buf+0x61/0xf0 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/tty_buffer.c:461
 paste_selection+0x250/0x340 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/vt/selection.c:408
 tioclinux+0xe5/0x450 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/vt/vt.c:3164
 vt_ioctl+0xde0/0x20e0 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/vt/vt_ioctl.c:823
 tty_ioctl+0xa2c/0x10c0 syzkaller/managers/upstream-kcsan-gce/kernel/drivers/tty/tty_io.c:2675
 vfs_ioctl syzkaller/managers/upstream-kcsan-gce/kernel/fs/ioctl.c:48 [inline]
 __do_sys_ioctl syzkaller/managers/upstream-kcsan-gce/kernel/fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xcb/0x140 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ioctl.c:739
 __x64_sys_ioctl+0x3f/0x50 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ioctl.c:739
 do_syscall_64+0x39/0x80 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4450 Comm: syz-executor.2 Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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