Index: Lib/test/pickletester.py
===================================================================
--- Lib/test/pickletester.py	(revision 67148)
+++ Lib/test/pickletester.py	(working copy)
@@ -1032,7 +1032,12 @@
         self.assertRaises(pickle.PicklingError, BadPickler().dump, 0)
         self.assertRaises(pickle.UnpicklingError, BadUnpickler().load)
 
+    def test_bad_input(self):
+        # Test issue4298
+        s = bytes([0x58, 0, 0, 0, 0x54])
+        self.assertRaises(EOFError, pickle.loads, s)
 
+
 class AbstractPersistentPicklerTests(unittest.TestCase):
 
     # This class defines persistent_id() and persistent_load()
Index: Modules/_pickle.c
===================================================================
--- Modules/_pickle.c	(revision 67148)
+++ Modules/_pickle.c	(working copy)
@@ -489,6 +489,11 @@
         return -1;
     }
 
+    if (PyBytes_GET_SIZE(data) != n) {
+        PyErr_SetNone(PyExc_EOFError);
+        return -1;
+    }
+
     Py_XDECREF(self->last_string);
     self->last_string = data;