From dda7611ec4a5ced89cebb3a9c48afc9c846a1f83 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Tue, 3 Jan 2017 16:39:48 +0100
Subject: USB: serial: keyspan_pda: verify endpoints at probe

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@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c
index e49ad0c..83523fc 100644
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -699,6 +699,19 @@ MODULE_FIRMWARE("keyspan_pda/keyspan_pda.fw");
 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_pda_device = {
 	.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,
 };
-- 
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