Strip control characters from sysfs attributes

Including them in the XML makes them unparsable.

https://bugzilla.redhat.com/show_bug.cgi?id=1184131

src/node_device/node_device_udev.c

@@ -191,7 +191,9 @@ static int udevGetUintProperty(struct udev_device *udev_device,
 
 
 /* This function allocates memory from the heap for the property
- * value.  That memory must be later freed by some other code. */
+ * value.  That memory must be later freed by some other code.
+ * Any control characters that cannot be printed in the XML are stripped
+ * from the string */
 static int udevGetDeviceSysfsAttr(struct udev_device *udev_device,
                                   const char *attr_name,
                                   char **attr_value)
@@ -233,6 +235,8 @@ static int udevGetStringSysfsAttr(struct udev_device *udev_device,
 
     ret = udevGetDeviceSysfsAttr(udev_device, attr_name, &tmp);
 
+    virStringStripControlChars(tmp);
+
     if (tmp != NULL && (STREQ(tmp, ""))) {
         VIR_FREE(tmp);
         tmp = NULL;