Index: Python/marshal.c
===================================================================
--- Python/marshal.c	(revision 75133)
+++ Python/marshal.c	(working copy)
@@ -589,7 +589,8 @@
 			ob->ob_size = n;
 			for (i = 0; i < size; i++) {
 				int digit = r_short(p);
-				if (digit < 0) {
+				if (digit < 0 ||
+				    (digit == 0 && i == size-1)) {
 					Py_DECREF(ob);
 					PyErr_SetString(PyExc_ValueError,
 							"bad marshal data");
Index: Lib/test/test_marshal.py
===================================================================
--- Lib/test/test_marshal.py	(revision 75133)
+++ 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,