validate direction number degree in SobolSequenceGenerator stream parser

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/random/SobolSequenceGenerator.java

@@ -205,6 +205,9 @@ private int initFromStream(final InputStream is) throws IOException {
                     dim = Integer.parseInt(st.nextToken());
                     if (dim >= 2 && dim <= dimension) { // we have found the right dimension
                         final int s = Integer.parseInt(st.nextToken());
+                        if (s < 1 || s > BITS) {
+                            throw new MathParseException(line, lineNumber);
+                        }
                         final int a = Integer.parseInt(st.nextToken());
                         final int[] m = new int[s + 1];
                         for (int i = 1; i <= s; i++) {

commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/random/SobolSequenceGeneratorTest.java

@@ -18,8 +18,11 @@
 
 import org.junit.Assert;
 
+import java.io.ByteArrayInputStream;
 import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
 
+import org.apache.commons.math4.legacy.exception.MathParseException;
 import org.apache.commons.math4.legacy.exception.OutOfRangeException;
 import org.junit.Before;
 import org.junit.Test;
@@ -91,6 +94,24 @@ public void testConstructor2() throws Exception{
         }
     }
 
+    @Test
+    public void testConstructorDegreeTooLarge() {
+        // direction number degree s = 60 exceeds the BITS (52) entries available
+        // per dimension; without range validation this indexes past direction[d]
+        // and throws ArrayIndexOutOfBoundsException instead of MathParseException.
+        final StringBuilder sb = new StringBuilder("d s a m_i\n2 60 0");
+        for (int i = 0; i < 60; i++) {
+            sb.append(" 1");
+        }
+        final InputStream is = new ByteArrayInputStream(sb.toString().getBytes(StandardCharsets.UTF_8));
+        try {
+            new SobolSequenceGenerator(2, is);
+            Assert.fail("an exception should have been thrown");
+        } catch (MathParseException e) {
+            // expected
+        }
+    }
+
     @Test
     public void testSkip() {
         double[] result = generator.skipTo(5);