Index: Python/marshal.c
===================================================================
--- Python/marshal.c	(revision 75105)
+++ Python/marshal.c	(working copy)
@@ -556,7 +556,7 @@
 r_PyLong(RFILE *p)
 {
 	PyLongObject *ob;
-	int size, i, j, md;
+	int size, i, j, md, shorts_in_top_digit;
 	long n;
 	digit d;
 
@@ -586,12 +586,22 @@
 		ob->ob_digit[i] = d;
 	}
 	d = 0;
-	for (j=0; j < (ABS(n)-1)%PyLong_MARSHAL_RATIO + 1; j++) {
+	shorts_in_top_digit = (ABS(n)-1) % PyLong_MARSHAL_RATIO + 1;
+	for (j=0; j < shorts_in_top_digit; j++) {
 		md = r_short(p);
 		if (md < 0 || md > PyLong_MARSHAL_BASE)
 			goto bad_digit;
+		/* topmost marshal digit should be nonzero */
+		if (md == 0 && j == shorts_in_top_digit - 1) {
+		  Py_DECREF(ob);
+		  PyErr_SetString(PyExc_ValueError,
+				  "bad marshal data (unnormalized long data)");
+		  return NULL;
+		}
 		d += (digit)md << j*PyLong_MARSHAL_SHIFT;
 	}
+	/* top digit should be nonzero, else the resulting PyLong won't be
+	   normalized */
 	ob->ob_digit[size-1] = d;
 	return (PyObject *)ob;
   bad_digit:
Index: Lib/test/test_marshal.py
===================================================================
--- Lib/test/test_marshal.py	(revision 75105)
+++ Lib/test/test_marshal.py	(working copy)
@@ -262,7 +262,12 @@
         testString = 'abc' * size
         marshal.dumps(testString)
 
+    def test_invalid_longs(self):
+        # Issue #7019: marshal.loads shouldn't produce unnormalized PyLongs
+        invalid_string = 'l\x02\x00\x00\x00\x00\x00\x00\x00'
+        self.assertRaises(ValueError, marshal.loads, invalid_string)
 
+
 def test_main():
     test_support.run_unittest(IntTestCase,
                               FloatTestCase,