From c3c9db89273fabc62ea1b48389d9a3000c1c03ae Mon Sep 17 00:00:00 2001
From: Jay Bosamiya <jaybosamiya@gmail.com>
Date: Sun, 18 Jun 2017 22:11:03 +0530
Subject: [PATCH] [2.7] bpo-30657: Check & prevent integer overflow in
 PyString_DecodeEscape (#2174)

---
 Misc/ACKS              | 1 +
 Misc/NEWS              | 3 +++
 Objects/stringobject.c | 8 +++++++-
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/Misc/ACKS b/Misc/ACKS
index 95be42717a0..a411bc5ffc8 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -152,6 +152,7 @@ Gregory Bond
 Matias Bordese
 Jonas Borgström
 Jurjen Bos
+Jay Bosamiya
 Peter Bosch
 Dan Boswell
 Eric Bouck
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -612,7 +612,13 @@ PyObject *PyString_DecodeEscape(const char *s,
     char *p, *buf;
     const char *end;
     PyObject *v;
-    Py_ssize_t newlen = recode_encoding ? 4*len:len;
+    Py_ssize_t newlen;
+    /* Check for integer overflow */
+    if (recode_encoding && (len > PY_SSIZE_T_MAX / 4)) {
+        PyErr_SetString(PyExc_OverflowError, "string is too large");
+        return NULL;
+    }
+    newlen = recode_encoding ? 4*len:len;
     v = PyString_FromStringAndSize((char *)NULL, newlen);
     if (v == NULL)
         return NULL;