Improve diagnostics for repeated text size overflow in SpEL

If the resulting size of repeated text in a SpEL expression (using the
repeat operator '*') would exceed MAX_REPEATED_TEXT_SIZE, we currently
throw a SpelEvaluationException with the
MAX_REPEATED_TEXT_SIZE_EXCEEDED message.

However, if the calculation of the repeated text size results in
integer overflow, our max size check fails to detect that, and
String#repeat(int) throws a preemptive OutOfMemoryError from which the
application immediately recovers.

To improve diagnostics for users, this commit ensures that we
consistently throw a SpelEvaluationException with the
MAX_REPEATED_TEXT_SIZE_EXCEEDED message when integer overflow occurs.

Closes gh-31341

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

@@ -123,7 +123,8 @@ public class OpMultiply extends Operator {
 	}
 
 	private void checkRepeatedTextSize(String text, int count) {
-		if (text.length() * count > MAX_REPEATED_TEXT_SIZE) {
+		int result = text.length() * count;
+		if (result < 0 || result > MAX_REPEATED_TEXT_SIZE) {
 			throw new SpelEvaluationException(getStartPosition(),
 					SpelMessage.MAX_REPEATED_TEXT_SIZE_EXCEEDED, MAX_REPEATED_TEXT_SIZE);
 		}

spring-expression/src/test/java/org/springframework/expression/spel/OperatorTests.java

@@ -579,6 +579,12 @@ class OperatorTests extends AbstractExpressionTests {
 
 		// 4 is the position of the '*' (repeat operator)
 		evaluateAndCheckError("'a' * 257", String.class, MAX_REPEATED_TEXT_SIZE_EXCEEDED, 4);
+
+		// Integer overflow: 2 * ((Integer.MAX_VALUE / 2) + 1) --> integer overflow
+		int repeatCount = (Integer.MAX_VALUE / 2) + 1;
+		assertThat(2 * repeatCount).isNegative();
+		// 5 is the position of the '*' (repeat operator)
+		evaluateAndCheckError("'ab' * " + repeatCount, String.class, MAX_REPEATED_TEXT_SIZE_EXCEEDED, 5);
 	}
 
 	@Test