usbip: usbip_detach: fix to check for invalid ports

usbip detach doesn't check for invalid ports and ports that are already
detached. It attempts to remove state file(s) without validating the port
and sends detach request to the driver for ports that are already detached.

Add check for invalid ports (port > maxports) and ports that are already
detached (status == VDEV_ST_NULL). Don't remove state files and don't send
detach request for invalid ports and ports that are already detached.

Add error and information messages that make sense.
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tools/usb/usbip/src/usbip_detach.c

@@ -46,6 +46,9 @@ static int detach_port(char *port)
 	int ret = 0;
 	uint8_t portnum;
 	char path[PATH_MAX+1];
+	int i;
+	struct usbip_imported_device *idev;
+	int found = 0;
 
 	unsigned int port_len = strlen(port);
 
@@ -55,28 +58,46 @@ static int detach_port(char *port)
 			return -1;
 		}
 
-	/* check max port */
-
 	portnum = atoi(port);
 
-	/* remove the port state file */
-
-	snprintf(path, PATH_MAX, VHCI_STATE_PATH"/port%d", portnum);
-
-	remove(path);
-	rmdir(VHCI_STATE_PATH);
-
 	ret = usbip_vhci_driver_open();
 	if (ret < 0) {
 		err("open vhci_driver");
 		return -1;
 	}
 
+	/* check for invalid port */
+	for (i = 0; i < vhci_driver->nports; i++) {
+		idev = &vhci_driver->idev[i];
+
+		if (idev->port == portnum) {
+			found = 1;
+			if (idev->status != VDEV_ST_NULL)
+				break;
+			info("Port %d is already detached!\n", idev->port);
+			goto call_driver_close;
+		}
+	}
+
+	if (!found) {
+		err("Invalid port %s > maxports %d",
+			port, vhci_driver->nports);
+		goto call_driver_close;
+	}
+
+	/* remove the port state file */
+	snprintf(path, PATH_MAX, VHCI_STATE_PATH"/port%d", portnum);
+
+	remove(path);
+	rmdir(VHCI_STATE_PATH);
+
 	ret = usbip_vhci_detach_device(portnum);
 	if (ret < 0) {
 		ret = -1;
+		err("Port %d detach request failed!\n", portnum);
 		goto call_driver_close;
 	}
+	info("Port %d is now detached!\n", portnum);
 
 call_driver_close:
 	usbip_vhci_driver_close();