CronSequenceGenerator prevents stack overflow in case of inverted range

Issue: SPR-14462

Author: jhoeller

spring-context/src/main/java/org/springframework/scheduling/support/CronSequenceGenerator.java

@@ -95,6 +95,7 @@ public CronSequenceGenerator(String expression, TimeZone timeZone) {
 		parse(expression);
 	}
 
+
 	/**
 	 * Return the cron pattern that this sequence generator has been built for.
 	 */
@@ -378,6 +379,10 @@ private int[] getRange(String field, int min, int max) {
 			throw new IllegalArgumentException("Range less than minimum (" + min + "): '" +
 					field + "' in expression \"" + this.expression + "\"");
 		}
+		if (result[0] > result[1]) {
+			throw new IllegalArgumentException("Invalid inverted range: '" + field +
+					"' in expression \"" + this.expression + "\"");
+		}
 		return result;
 	}
 
@@ -388,6 +393,7 @@ private int[] getRange(String field, int min, int max) {
 	 * fields separated by single spaces.
 	 * @param expression the expression to evaluate
 	 * @return {@code true} if the given expression is a valid cron expression
+	 * @since 4.3
 	 */
 	public static boolean isValidExpression(String expression) {
 		String[] fields = StringUtils.tokenizeToStringArray(expression, " ");

spring-context/src/test/java/org/springframework/scheduling/support/CronSequenceGeneratorTests.java

@@ -56,6 +56,26 @@ public void withNegativeIncrement() {
 		new CronSequenceGenerator("*/-1 * * * * *").next(new Date(2012, 6, 1, 9, 0));
 	}
 
+	@Test(expected = IllegalArgumentException.class)
+	public void withInvertedMinuteRange() {
+		new CronSequenceGenerator("* 6-5 * * * *").next(new Date(2012, 6, 1, 9, 0));
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void withInvertedHourRange() {
+		new CronSequenceGenerator("* * 6-5 * * *").next(new Date(2012, 6, 1, 9, 0));
+	}
+
+	@Test
+	public void withSameMinuteRange() {
+		new CronSequenceGenerator("* 6-6 * * * *").next(new Date(2012, 6, 1, 9, 0));
+	}
+
+	@Test
+	public void withSameHourRange() {
+		new CronSequenceGenerator("* * 6-6 * * *").next(new Date(2012, 6, 1, 9, 0));
+	}
+
 	@Test
 	public void validExpression() {
 		assertTrue(CronSequenceGenerator.isValidExpression("0 */2 1-4 * * *"));