query description added

cpp/ql/src/experimental/Security/CVE/cve-2016-6480.ql

@@ -1,3 +1,19 @@
+/**
+ * @name Linux kernel double-fetch vulnerability detection
+ * @description Double-fetch is a very common vulnerability pattern 
+ *              in linux kernel, attacker can exploit double-fetch 
+ *              issues to obatain root privilege. 
+ *              Double-fetch is caused by fetching data from user 
+ *              mode by calling copy_from_user twice, CVE-2016-6480
+ *              is quite a good example for your information.
+ * @kind problem
+ * @id cpp/linux-kernel-double-fetch-vulnerability
+ * @problem.severity warning
+ * @security-severity 7.5
+ * @tags security
+ *       external/cwe/cwe-362
+ */
+
 import cpp
 
 class CopyFromUserFunctionCall extends FunctionCall{