[PATCH 4.4 030/101] USB: serial: keyspan_pda: verify endpoints at probe

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@xxxxxxxxxx>

commit 5d9b0f859babe96175cd33d7162a9463a875ffde upstream.

Check for the expected endpoints in attach() and fail loudly if not
present.

Note that failing to do this appears to be benign since da280e348866
("USB: keyspan_pda: clean up write-urb busy handling") which prevents a
NULL-pointer dereference in write() by never marking a non-existent
write-urb as free.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/serial/keyspan_pda.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -699,6 +699,19 @@ MODULE_FIRMWARE("keyspan_pda/keyspan_pda
 MODULE_FIRMWARE("keyspan_pda/xircom_pgs.fw");
 #endif
 
+static int keyspan_pda_attach(struct usb_serial *serial)
+{
+	unsigned char num_ports = serial->num_ports;
+
+	if (serial->num_bulk_out < num_ports ||
+			serial->num_interrupt_in < num_ports) {
+		dev_err(&serial->interface->dev, "missing endpoints\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
 static int keyspan_pda_port_probe(struct usb_serial_port *port)
 {
 
@@ -776,6 +789,7 @@ static struct usb_serial_driver keyspan_
 	.break_ctl =		keyspan_pda_break_ctl,
 	.tiocmget =		keyspan_pda_tiocmget,
 	.tiocmset =		keyspan_pda_tiocmset,
+	.attach =		keyspan_pda_attach,
 	.port_probe =		keyspan_pda_port_probe,
 	.port_remove =		keyspan_pda_port_remove,
 };