[PATCH 3.16 162/370] USB: serial: kobil_sct: fix NULL-deref in write

Ben Hutchings
2017-03-10T13:57:34Z

From: Johan Hovold <johan@kernel.org>

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")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/usb/serial/kobil_sct.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

--- 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_de
.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;