LibRegex: Check code unit count range when accessing by code unit count

Author: https://github.com/alimpfard
Commit: e43b478920
Pull-request: https://github.com/SerenityOS/serenity/pull/14592
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibRegex/RegexByteCode.cpp

@@ -532,7 +532,7 @@ ALWAYS_INLINE ExecutionResult OpCode_Compare::execute(MatchInput const& input, M
 
         } else if (compare_type == CharacterCompareType::CharClass) {
 
-            if (input.view.length() <= state.string_position)
+            if (input.view.length() <= state.string_position_in_code_units)
                 return ExecutionResult::Failed_ExecuteLowPrioForks;
 
             auto character_class = (CharClass)m_bytecode->at(offset++);