From 64ea192b73e39e877d8b39ce6584fa580eb0e9b4 Mon Sep 17 00:00:00 2001
From: Benjamin Peterson <benjamin@python.org>
Date: Wed, 20 Jan 2016 22:23:44 -0800
Subject: [PATCH] prevent buffer overflow in get_data (closes #26171)

---
 Misc/NEWS           | 3 +++
 Modules/zipimport.c | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/Misc/NEWS b/Misc/NEWS
index 0d176456e6d..995ad1be6a5 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -36,6 +36,9 @@ Core and Builtins
   __str__, __trunc__, and __float__ returning instances of subclasses of
   str, long, and float to subclasses of str, long, and float correspondingly.
 
+- Issue #26171: Fix possible integer overflow and heap corruption in
+  zipimporter.get_data().
+
 Library
 -------
 
diff --git a/Modules/zipimport.c b/Modules/zipimport.c
index 27a082dcbad..006be3c59a8 100644
--- a/Modules/zipimport.c
+++ b/Modules/zipimport.c
@@ -895,6 +895,11 @@ get_data(char *archive, PyObject *toc_entry)
         PyMarshal_ReadShortFromFile(fp);        /* local header size */
     file_offset += l;           /* Start of file data */
 
+    if (data_size > LONG_MAX - 1) {
+        fclose(fp);
+        PyErr_NoMemory();
+        return NULL;
+    }
     raw_data = PyString_FromStringAndSize((char *)NULL, compress == 0 ?
                                           data_size : data_size + 1);
     if (raw_data == NULL) {