[Yaml] Fixed infinite loop when parser goes through an additional and invalid closing tag

Instead of letting the parser goes in an infinite loop, throw an exception when the additional and invalid is found

Author: alexandre-daubois

Parser.php

@@ -1225,6 +1225,10 @@ private function lexUnquotedString(int &$cursor): string
         $offset = $cursor;
         $cursor += strcspn($this->currentLine, '[]{},: ', $cursor);
 
+        if ($cursor === $offset) {
+            throw new ParseException('Malformed unquoted YAML string.');
+        }
+
         return substr($this->currentLine, $offset, $cursor - $offset);
     }
 

Tests/ParserTest.php

@@ -2676,6 +2676,25 @@ public function testParseValueWithNegativeModifiers()
         );
     }
 
+    public function testThrowExceptionIfInvalidAdditionalClosingTagOccurs()
+    {
+        $yaml = '{
+            "object": {
+                    "array": [
+                        "a",
+                        "b",
+                        "c"
+                    ]
+                ],
+            }
+        }';
+
+        $this->expectException(ParseException::class);
+        $this->expectExceptionMessage('Malformed unquoted YAML string at line 8 (near "                ],").');
+
+        $this->parser->parse($yaml);
+    }
+
     public function testWhitespaceAtEndOfLine()
     {
         $yaml = "\nfoo:\n    arguments: [ '@bar' ]  \n";