Issue #27507: Merge overflow check from 3.5

vadmium · vadmium · commit bd09f15b6918 · 2016-07-18T08:18:32.000Z
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -10,6 +10,9 @@ What's New in Python 3.6.0 alpha 4
 Core and Builtins
 -----------------
 
+- Issue #27507: Add integer overflow check in bytearray.extend().  Patch by
+  Xiang Zhang.
+
 - Issue #27419: Standard __import__() no longer look up "__import__" in globals
   or builtins for importing submodules or "from import".  Fixed a crash if
   raise a warning about unabling to resolve package from __spec__ or
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
@@ -1642,7 +1642,17 @@ bytearray_extend(PyByteArrayObject *self, PyObject *iterable_of_ints)
         Py_DECREF(item);
 
         if (len >= buf_size) {
-            buf_size = len + (len >> 1) + 1;
+            Py_ssize_t addition;
+            if (len == PY_SSIZE_T_MAX) {
+                Py_DECREF(it);
+                Py_DECREF(bytearray_obj);
+                return PyErr_NoMemory();
+            }
+            addition = len >> 1;
+            if (addition > PY_SSIZE_T_MAX - len - 1)
+                buf_size = PY_SSIZE_T_MAX;
+            else
+                buf_size = len + addition + 1;
             if (PyByteArray_Resize((PyObject *)bytearray_obj, buf_size) < 0) {
                 Py_DECREF(it);
                 Py_DECREF(bytearray_obj);
