Prevent IndexOutOfRangeException in RegexInterpreter (#97916)

* Prevent IndexOutOfRangeException in RegexInterpreter

This update fixes the IndexOutOfRangeException in RegexInterpreter by enhancing the `TrackPush` and `TrackPush2` methods. The adjustment involves checking the runtrack position before decrementing it, ensuring that it doesn't become negative, which was the root cause of the exception. This prevents potential out-of-range errors when handling large numbers of repetitions in regular expressions.

Fix #62094

* Changed to call EnsureStorage() unconditionally.

If EnsureStorage() is called unconditionally, the array will be expanded, so the position will never become negative. When the conditions inside EnsureStorage() are true, it might be necessary to expand the array, regardless of the comparison between newpos and codepos.

https://github.com/dotnet/runtime/blob/6ebc8bd86dbc780b2a2a7daf3ab6020f9104f09e/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.MultipleMatches.Tests.cs#L461-L469

Before the change, in this test case, EnsureStorage() is not called because newpos == codepos == 6 from the first time until an exception occurs.

Fix #62049

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexInterpreter.cs

@@ -53,10 +53,7 @@ private void Advance(int i)
         private void Goto(int newpos)
         {
             // When branching backward, ensure storage.
-            if (newpos < _codepos)
-            {
-                EnsureStorage();
-            }
+            EnsureStorage();
 
             _codepos = newpos;
             SetOperator((RegexOpcode)_code.Codes[newpos]);
@@ -144,10 +141,7 @@ private void Backtrack()
             SetOperator((RegexOpcode)(_code.Codes[newpos] | back));
 
             // When branching backward, ensure storage.
-            if (newpos < _codepos)
-            {
-                EnsureStorage();
-            }
+            EnsureStorage();
 
             _codepos = newpos;
         }

src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.MultipleMatches.Tests.cs

@@ -454,19 +454,15 @@ public static IEnumerable<object[]> Matches_TestData()
                     };
                 }
 
-                if (engine != RegexEngine.Interpreter && // these tests currently fail with RegexInterpreter
-                    RuntimeFeature.IsDynamicCodeCompiled) // if dynamic code isn't compiled, RegexOptions.Compiled falls back to the interpreter, for which these tests currently fail
+                // Fails on .NET Framework: [ActiveIssue("https://github.com/dotnet/runtime/issues/62094")]
+                yield return new object[]
                 {
-                    // Fails on interpreter and .NET Framework: [ActiveIssue("https://github.com/dotnet/runtime/issues/62094")]
-                    yield return new object[]
+                    engine, @"(?:){93}", "x", RegexOptions.None, new[]
                     {
-                        engine, @"(?:){93}", "x", RegexOptions.None, new[]
-                        {
-                            new CaptureData("", 0, 0),
-                            new CaptureData("", 1, 0)
-                        }
-                    };
-                }
+                        new CaptureData("", 0, 0),
+                        new CaptureData("", 1, 0)
+                    }
+                };
 #endif
             }
         }