The driver can be crashed with devices that expose crafted
descriptors with too few endpoints.
See:
http://seclists.org/bugtraq/2016/Mar/61

Signed-off-by: Oliver Neukum <oneu...@suse.com>

v1 - added sanity checks
v2 - moved them to probe() to fix problems Johan pointed out
---
 drivers/usb/serial/digi_acceleport.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/digi_acceleport.c 
b/drivers/usb/serial/digi_acceleport.c
index 12b0e67..dab1dcf 100644
--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -1252,7 +1252,8 @@ static int digi_port_init(struct usb_serial_port *port, 
unsigned port_num)
 static int digi_startup(struct usb_serial *serial)
 {
        struct digi_serial *serial_priv;
-       int ret;
+       int ret = -ENODEV;
+       int i;
 
        serial_priv = kzalloc(sizeof(*serial_priv), GFP_KERNEL);
        if (!serial_priv)
@@ -1260,18 +1261,31 @@ static int digi_startup(struct usb_serial *serial)
 
        spin_lock_init(&serial_priv->ds_serial_lock);
        serial_priv->ds_oob_port_num = serial->type->num_ports;
+
+       /* Check whether the expected number of ports matches the device */
+       if (serial->num_ports < serial_priv->ds_oob_port_num)
+               goto error;
+       /* all features must be present */
+       for (i = 0; i < serial->type->num_ports + 1 ; i++) {
+               if (!serial->port[i]->read_urb)
+                       goto error;
+               if (!serial->port[i]->write_urb)
+                       goto error;
+       }
+
        serial_priv->ds_oob_port = serial->port[serial_priv->ds_oob_port_num];
 
        ret = digi_port_init(serial_priv->ds_oob_port,
                                                serial_priv->ds_oob_port_num);
-       if (ret) {
-               kfree(serial_priv);
-               return ret;
-       }
+       if (ret)
+               goto error;
 
        usb_set_serial_data(serial, serial_priv);
 
        return 0;
+error:
+       kfree(serial_priv);
+       return ret;
 }
 
 
-- 
2.1.4

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