release/4.8.18/USB-serial-kobil_sct-fix-NULL-deref-in-write.patch

From 2a45e50d76bb1cad375cbff251912ea7c9bde3a9 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Tue, 3 Jan 2017 16:39:49 +0100
Subject: [PATCH] USB: serial: kobil_sct: fix NULL-deref in write

commit 21ce57840243c7b70fbc1ebd3dceeb70bb6e9e09 upstream.

Fix NULL-pointer dereference in write() should the device lack the
expected interrupt-out endpoint:

Unable to handle kernel NULL pointer dereference at virtual address 00000054
...
PC is at kobil_write+0x144/0x2a0 [kobil_sct]

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/usb/serial/kobil_sct.c b/drivers/usb/serial/kobil_sct.c
index 2363654cafc9..813035f51fe7 100644
--- a/drivers/usb/serial/kobil_sct.c
+++ b/drivers/usb/serial/kobil_sct.c
@@ -51,6 +51,7 @@
 
 
 /* Function prototypes */
+static int kobil_attach(struct usb_serial *serial);
 static int kobil_port_probe(struct usb_serial_port *probe);
 static int kobil_port_remove(struct usb_serial_port *probe);
 static int  kobil_open(struct tty_struct *tty, struct usb_serial_port *port);
@@ -86,6 +87,7 @@ static struct usb_serial_driver kobil_device = {
 	.description =		"KOBIL USB smart card terminal",
 	.id_table =		id_table,
 	.num_ports =		1,
+	.attach =		kobil_attach,
 	.port_probe =		kobil_port_probe,
 	.port_remove =		kobil_port_remove,
 	.ioctl =		kobil_ioctl,
@@ -113,6 +115,16 @@ struct kobil_private {
 };
 
 
+static int kobil_attach(struct usb_serial *serial)
+{
+	if (serial->num_interrupt_out < serial->num_ports) {
+		dev_err(&serial->interface->dev, "missing interrupt-out endpoint\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
 static int kobil_port_probe(struct usb_serial_port *port)
 {
 	struct usb_serial *serial = port->serial;
-- 
2.10.1