use toUnicode in RegexTreeView

Author: erik-krogh

python/ql/lib/semmle/python/RegexTreeView.qll

@@ -458,9 +458,10 @@ class RegExpEscape extends RegExpNormalChar {
     or
     this.getUnescaped() = "t" and result = "\t"
     or
-    // TODO: Find a way to include a formfeed character
-    // this.getUnescaped() = "f" and result = ""
-    // or
+    this.getUnescaped() = "f" and result = 12.toUnicode()
+    or
+    this.getUnescaped() = "v" and result = 11.toUnicode()
+    or
     isUnicode() and
     result = getUnicode()
   }

python/ql/test/query-tests/Security/CWE-730-ReDoS/ReDoS.expected

@@ -35,6 +35,9 @@
 | redos.py:139:25:139:31 | (\\w\|G)* | This part of the regular expression may cause exponential backtracking on strings containing many repetitions of 'G'. |
 | redos.py:145:25:145:32 | (\\d\|\\w)* | This part of the regular expression may cause exponential backtracking on strings containing many repetitions of '0'. |
 | redos.py:148:25:148:31 | (\\d\|5)* | This part of the regular expression may cause exponential backtracking on strings containing many repetitions of '5'. |
+| redos.py:151:25:151:34 | (\\s\|[\\f])* | This part of the regular expression may cause exponential backtracking on strings containing many repetitions of '\u000c'. |
+| redos.py:154:25:154:38 | (\\s\|[\\v]\|\\\\v)* | This part of the regular expression may cause exponential backtracking on strings containing many repetitions of '\u000b'. |
+| redos.py:157:25:157:34 | (\\f\|[\\f])* | This part of the regular expression may cause exponential backtracking on strings containing many repetitions of '\u000c'. |
 | redos.py:160:25:160:32 | (\\W\|\\D)* | This part of the regular expression may cause exponential backtracking on strings containing many repetitions of ' '. |
 | redos.py:163:25:163:32 | (\\S\|\\w)* | This part of the regular expression may cause exponential backtracking on strings containing many repetitions of '0'. |
 | redos.py:166:25:166:34 | (\\S\|[\\w])* | This part of the regular expression may cause exponential backtracking on strings containing many repetitions of '0'. |