USB: serial: kobil_sct: fix NULL-deref in write

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>

diff --git a/drivers/usb/serial/kobil_sct.c b/drivers/usb/serial/kobil_sct.c
index 2363654cafc9b79de61a30bcc00b7f875c470b60..813035f51fe73a4e0de69ce76e6c3329ba4d376c 100644 (file)
--- 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;