[PATCH 3.16 116/132] USB: rio500: refuse more than one device at a time

[Ben Hutchings]

3.16.74-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Oliver Neukum <oneukum@xxxxxxxx>

commit 3864d33943b4a76c6e64616280e98d2410b1190f upstream.

This driver is using a global variable. It cannot handle more than
one device at a time. The issue has been existing since the dawn
of the driver.

Signed-off-by: Oliver Neukum <oneukum@xxxxxxxx>
Reported-by: syzbot+35f04d136fc975a70da4@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/usb/misc/rio500.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

--- a/drivers/usb/misc/rio500.c
+++ b/drivers/usb/misc/rio500.c
@@ -464,15 +464,23 @@ static int probe_rio(struct usb_interfac
 {
 	struct usb_device *dev = interface_to_usbdev(intf);
 	struct rio_usb_data *rio = &rio_instance;
-	int retval;
+	int retval = 0;
 
-	dev_info(&intf->dev, "USB Rio found at address %d\n", dev->devnum);
+	mutex_lock(&rio500_mutex);
+	if (rio->present) {
+		dev_info(&intf->dev, "Second USB Rio at address %d refused\n", dev->devnum);
+		retval = -EBUSY;
+		goto bail_out;
+	} else {
+		dev_info(&intf->dev, "USB Rio found at address %d\n", dev->devnum);
+	}
 
 	retval = usb_register_dev(intf, &usb_rio_class);
 	if (retval) {
 		dev_err(&dev->dev,
 			"Not able to get a minor for this device.\n");
-		return -ENOMEM;
+		retval = -ENOMEM;
+		goto bail_out;
 	}
 
 	rio->rio_dev = dev;
@@ -481,7 +489,8 @@ static int probe_rio(struct usb_interfac
 		dev_err(&dev->dev,
 			"probe_rio: Not enough memory for the output buffer\n");
 		usb_deregister_dev(intf, &usb_rio_class);
-		return -ENOMEM;
+		retval = -ENOMEM;
+		goto bail_out;
 	}
 	dev_dbg(&intf->dev, "obuf address:%p\n", rio->obuf);
 
@@ -490,7 +499,8 @@ static int probe_rio(struct usb_interfac
 			"probe_rio: Not enough memory for the input buffer\n");
 		usb_deregister_dev(intf, &usb_rio_class);
 		kfree(rio->obuf);
-		return -ENOMEM;
+		retval = -ENOMEM;
+		goto bail_out;
 	}
 	dev_dbg(&intf->dev, "ibuf address:%p\n", rio->ibuf);
 
@@ -498,8 +508,10 @@ static int probe_rio(struct usb_interfac
 
 	usb_set_intfdata (intf, rio);
 	rio->present = 1;
+bail_out:
+	mutex_unlock(&rio500_mutex);
 
-	return 0;
+	return retval;
 }
 
 static void disconnect_rio(struct usb_interface *intf)