--- /dev/null
+From 2ad5692db72874f02b9ad551d26345437ea4f7f3 Mon Sep 17 00:00:00 2001
+From: Johan Hovold <johan@kernel.org>
+Date: Mon, 26 Apr 2021 10:11:49 +0200
+Subject: net: hso: fix NULL-deref on disconnect regression
+
+From: Johan Hovold <johan@kernel.org>
+
+commit 2ad5692db72874f02b9ad551d26345437ea4f7f3 upstream.
+
+Commit 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device
+unregistration") fixed the racy minor allocation reported by syzbot, but
+introduced an unconditional NULL-pointer dereference on every disconnect
+instead.
+
+Specifically, the serial device table must no longer be accessed after
+the minor has been released by hso_serial_tty_unregister().
+
+Fixes: 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device unregistration")
+Cc: stable@vger.kernel.org
+Cc: Anirudh Rayabharam <mail@anirudhrb.com>
+Reported-by: Leonardo Antoniazzi <leoanto@aruba.it>
+Signed-off-by: Johan Hovold <johan@kernel.org>
+Reviewed-by: Anirudh Rayabharam <mail@anirudhrb.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/net/usb/hso.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/net/usb/hso.c
++++ b/drivers/net/usb/hso.c
+@@ -3115,7 +3115,7 @@ static void hso_free_interface(struct us
+ cancel_work_sync(&serial_table[i]->async_put_intf);
+ cancel_work_sync(&serial_table[i]->async_get_intf);
+ hso_serial_tty_unregister(serial);
+- kref_put(&serial_table[i]->ref, hso_serial_ref_free);
++ kref_put(&serial->parent->ref, hso_serial_ref_free);
+ }
+ }
+