hso: fix NULL-deref on tty open

BugLink: https://bugs.launchpad.net/bugs/1848274
[ Upstream commit 8353da9fa69722b54cba82b2ec740afd3d438748 ]

Fix NULL-pointer dereference on tty open due to a failure to handle a
missing interrupt-in endpoint when probing modem ports:

	BUG: kernel NULL pointer dereference, address: 0000000000000006
	...
	RIP: 0010:tiocmget_submit_urb+0x1c/0xe0 [hso]
	...
	Call Trace:
	hso_start_serial_device+0xdc/0x140 [hso]
	hso_serial_open+0x118/0x1b0 [hso]
	tty_open+0xf1/0x490

Fixes: 542f54823614 ("tty: Modem functions for the HSO driver")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index cac3a34022376e26a47db31114eb4a01cfdaae51..6fda6b4968df080d1c511e1d755c8cc641d8cff8 100644 (file)
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -2630,14 +2630,18 @@ static struct hso_device *hso_create_bulk_serial_device(
                 */
                if (serial->tiocmget) {
                        tiocmget = serial->tiocmget;
+                       tiocmget->endp = hso_get_ep(interface,
+                                                   USB_ENDPOINT_XFER_INT,
+                                                   USB_DIR_IN);
+                       if (!tiocmget->endp) {
+                               dev_err(&interface->dev, "Failed to find INT IN ep\n");
+                               goto exit;
+                       }
+
                        tiocmget->urb = usb_alloc_urb(0, GFP_KERNEL);
                        if (tiocmget->urb) {
                                mutex_init(&tiocmget->mutex);
                                init_waitqueue_head(&tiocmget->waitq);
-                               tiocmget->endp = hso_get_ep(
-                                       interface,
-                                       USB_ENDPOINT_XFER_INT,
-                                       USB_DIR_IN);
                        } else
                                hso_free_tiomget(serial);
                }