USB: usbfs: fix potential infoleak in devio

The stack object “ci” has a total size of 8 bytes. Its last 3 bytes
are padding bytes which are not initialized and leaked to userland
via “copy_to_user”.

Signed-off-by: Kangjie Lu <kjlu@gatech.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
static int proc_disconnectsignal_compat(struct usb_dev_state *ps, void __user *arg)
{
	struct usbdevfs_disconnectsignal32 ds;

	if (copy_from_user(&ds, arg, sizeof(ds)))
		return -EFAULT;
	ps->discsignr = ds.signr;
	ps->disccontext = compat_ptr(ds.context);
	return 0;
}

static int proc_disconnectsignal_compat(struct usb_dev_state *ps, void __user *arg)
{
	struct usbdevfs_disconnectsignal32 ds;

	if (copy_from_user(&ds, arg, sizeof(ds)))
		return -EFAULT;
	ps->discsignr = ds.signr;
	ps->disccontext = compat_ptr(ds.context);
	return 0;
}
