Staging: usbip: Fix the warning of unchecked sscanf return value.

The return value of sscanf in stub_dev.c is not checked. This patch
adds the checking of the return value.
Signed-off-by: Elena Oat <oat.elena@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/usbip/stub_dev.c

@@ -87,13 +87,16 @@ static ssize_t store_sockfd(struct device *dev, struct device_attribute *attr,
 	int sockfd = 0;
 	struct socket *socket;
 	ssize_t err = -EINVAL;
+	int rv;
 
 	if (!sdev) {
 		dev_err(dev, "sdev is null\n");
 		return -ENODEV;
 	}
 
-	sscanf(buf, "%d", &sockfd);
+	rv = sscanf(buf, "%d", &sockfd);
+	if (rv != 1)
+		return -EINVAL;
 
 	if (sockfd != -1) {
 		dev_info(dev, "stub up\n");