diff -r eaac55703796 Modules/_testbuffer.c
--- a/Modules/_testbuffer.c	Wed Aug 22 17:45:52 2012 +0200
+++ b/Modules/_testbuffer.c	Thu Aug 23 10:03:59 2012 +0200
@@ -2362,6 +2362,11 @@ get_ascii_order(PyObject *order)
 
     ord = PyBytes_AS_STRING(ascii_order)[0];
     Py_DECREF(ascii_order);
+
+    if (ord != 'C' && ord != 'F' && ord != 'A') {
+        PyErr_Format(PyExc_ValueError, "invalid order, must be C, F or A, got %c", order)
+        return CHAR_MAX;
+    }
     return ord;
 }
 
@@ -2388,12 +2393,15 @@ get_contiguous(PyObject *self, PyObject 
     if (type == -1 && PyErr_Occurred()) {
         return NULL;
     }
-
-    ord = get_ascii_order(order);
-    if (ord == CHAR_MAX) {
+    if (buffertype != PyBUF_READ && buffertype != PyBUF_WRITE) {
+        PyErr_SetString(PyExc_ValueError, "invalid buffer type");
         return NULL;
     }
 
+    ord = get_ascii_order(order);
+    if (ord == CHAR_MAX)
+        return NULL;
+
     return PyMemoryView_GetContiguous(obj, (int)type, ord);
 }