[PATCH 1/4] rio500: refuse more than one device at a time

[Oliver Neukum]

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.

V2: Fixed locking in probe()
    Fixed Documentation

Signed-off-by: Oliver Neukum <oneu...@suse.com>
Reported-by: syzbot+35f04d136fc975a70...@syzkaller.appspotmail.com
---
 drivers/usb/misc/rio500.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/misc/rio500.c b/drivers/usb/misc/rio500.c
index 13e4889bc34f..fa921ae60ffa 100644
--- a/drivers/usb/misc/rio500.c
+++ b/drivers/usb/misc/rio500.c
@@ -447,15 +447,23 @@ static int probe_rio(struct usb_interface *intf,
 {
        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;
@@ -464,7 +472,8 @@ static int probe_rio(struct usb_interface *intf,
                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);
 
@@ -473,7 +482,8 @@ static int probe_rio(struct usb_interface *intf,
                        "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);
 
@@ -481,8 +491,10 @@ static int probe_rio(struct usb_interface *intf,
 
        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)
-- 
2.16.4