Improve diagnostics in SpEL for large array creation

Attempting to create a large array in a SpEL expression can result in
an OutOfMemoryError. Although the JVM recovers from that, the error
message is not very helpful to the user.

This commit improves the diagnostics in SpEL for large array creation
by throwing a SpelEvaluationException with a meaningful error message
in order to improve diagnostics for the user.

Closes spring-projectsgh-28145

spring-expression/src/main/java/org/springframework/expression/spel/SpelMessage.java

@@ -251,8 +251,13 @@ public enum SpelMessage {
 	MISSING_SELECTION_EXPRESSION(Kind.ERROR, 1071,
 			"A required selection expression has not been specified"),
 
-	EXCEPTION_RUNNING_COMPILED_EXPRESSION(Kind.ERROR,1072,
-			"An exception occurred whilst evaluating a compiled expression");
+	/** @since 4.1 */
+	EXCEPTION_RUNNING_COMPILED_EXPRESSION(Kind.ERROR, 1072,
+			"An exception occurred whilst evaluating a compiled expression"),
+
+	/** @since 5.3.17 */
+	MAX_ARRAY_ELEMENTS_THRESHOLD_EXCEEDED(Kind.ERROR, 1075,
+			"Array declares too many elements, exceeding the threshold of ''{0}''");
 
 
 	private final Kind kind;

spring-expression/src/main/java/org/springframework/expression/spel/ast/ConstructorReference.java

@@ -51,10 +51,18 @@
  *
  * @author Andy Clement
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 3.0
  */
 public class ConstructorReference extends SpelNodeImpl {
 
+	/**
+	 * Maximum number of elements permitted in an array declaration, applying
+	 * to one-dimensional as well as multi-dimensional arrays.
+	 * @since 5.3.17
+	 */
+	private static final int MAX_ARRAY_ELEMENTS = 256 * 1024; // 256K
+
 	private boolean isArrayConstructor = false;
 
 	private SpelNodeImpl[] dimensions;
@@ -256,14 +264,19 @@ private TypedValue createArray(ExpressionState state) throws EvaluationException
 			if (this.dimensions.length == 1) {
 				TypedValue o = this.dimensions[0].getTypedValue(state);
 				int arraySize = ExpressionUtils.toInt(typeConverter, o);
+				checkNumElements(arraySize);
 				newArray = Array.newInstance(componentType, arraySize);
 			}
 			else {
 				// Multi-dimensional - hold onto your hat!
 				int[] dims = new int[this.dimensions.length];
+				long numElements = 1;
 				for (int d = 0; d < this.dimensions.length; d++) {
 					TypedValue o = this.dimensions[d].getTypedValue(state);
-					dims[d] = ExpressionUtils.toInt(typeConverter, o);
+					int arraySize = ExpressionUtils.toInt(typeConverter, o);
+					dims[d] = arraySize;
+					numElements *= arraySize;
+					checkNumElements(numElements);
 				}
 				newArray = Array.newInstance(componentType, dims);
 			}
@@ -323,6 +336,13 @@ else if (arrayTypeCode == TypeCode.BYTE) {
 		return new TypedValue(newArray);
 	}
 
+	private void checkNumElements(long numElements) {
+		if (numElements >= MAX_ARRAY_ELEMENTS) {
+			throw new SpelEvaluationException(getStartPosition(),
+					SpelMessage.MAX_ARRAY_ELEMENTS_THRESHOLD_EXCEEDED, MAX_ARRAY_ELEMENTS);
+		}
+	}
+
 	private void populateReferenceTypeArray(ExpressionState state, Object newArray, TypeConverter typeConverter,
 			InlineList initializer, Class<?> componentType) {