From 90cfde985ef08e8372ffefda2156f8091f65efe6 Mon Sep 17 00:00:00 2001
From: Sam Brannen <sbrannen@vmware.com>
Date: Thu, 31 Mar 2022 09:32:52 +0200
Subject: [PATCH] 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 gh-28257
---
 .../expression/spel/SpelMessage.java          |  9 +++++--
 .../spel/ast/ConstructorReference.java        | 24 +++++++++++++++++--
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/SpelMessage.java b/spring-expression/src/main/java/org/springframework/expression/spel/SpelMessage.java
index 8998cb298889..a3f588a1de4d 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/SpelMessage.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/SpelMessage.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,6 +31,7 @@
  *
  * @author Andy Clement
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 3.0
  */
 public enum SpelMessage {
@@ -255,7 +256,11 @@ public enum SpelMessage {
 
 	/** @since 4.3.17 */
 	FLAWED_PATTERN(Kind.ERROR, 1073,
-			"Failed to efficiently evaluate pattern ''{0}'': consider redesigning it");
+			"Failed to efficiently evaluate pattern ''{0}'': consider redesigning it"),
+
+	/** @since 5.2.20 */
+	MAX_ARRAY_ELEMENTS_THRESHOLD_EXCEEDED(Kind.ERROR, 1075,
+			"Array declares too many elements, exceeding the threshold of ''{0}''");
 
 
 	private final Kind kind;
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/ConstructorReference.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/ConstructorReference.java
index d42a375410f6..11d8e5dc72a7 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/ConstructorReference.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/ConstructorReference.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -53,10 +53,18 @@
  *
  * @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 5.2.20
+	 */
+	private static final int MAX_ARRAY_ELEMENTS = 256 * 1024; // 256K
+
 	private final boolean isArrayConstructor;
 
 	@Nullable
@@ -259,14 +267,19 @@ private TypedValue createArray(ExpressionState state) throws EvaluationException
 					// Shortcut for 1-dimensional
 					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);
 				}
@@ -327,6 +340,13 @@ else if (arrayTypeCode == TypeCode.SHORT) {
 		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) {