[Python-checkins] cpython (2.7): fix possible overflow in encode_basestring_ascii (#23369)

[benjamin.peterson]

https://hg.python.org/cpython/rev/6fa0ebfdc136
changeset:   102635:6fa0ebfdc136
branch:      2.7
parent:      102632:b1e4c8a3e786
user:        Benjamin Peterson <benjamin at python.org>
date:        Sat Aug 13 16:47:25 2016 -0700
summary:
  fix possible overflow in encode_basestring_ascii (#23369)

files:
  Misc/NEWS       |  3 +++
  Modules/_json.c |  4 ++++
  2 files changed, 7 insertions(+), 0 deletions(-)


diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -29,6 +29,9 @@
 Library
 -------
 
+- Issue #23369: Fixed possible integer overflow in
+  _json.encode_basestring_ascii.
+
 - Issue #27568: Prevent HTTPoxy attack (CVE-2016-1000110). Ignore the
   HTTP_PROXY variable when REQUEST_METHOD environment is set, which indicates
   that the script is in CGI mode.
diff --git a/Modules/_json.c b/Modules/_json.c
--- a/Modules/_json.c
+++ b/Modules/_json.c
@@ -211,6 +211,10 @@
     input_unicode = PyUnicode_AS_UNICODE(pystr);
 
     /* One char input can be up to 6 chars output, estimate 4 of these */
+    if (input_chars > (PY_SSIZE_T_MAX - 2)/ MAX_EXPANSION) {
+        PyErr_SetString(PyExc_OverflowError, "string is too long to escape");
+        return NULL;
+    }
     output_size = 2 + (MIN_EXPANSION * 4) + input_chars;
     max_output_size = 2 + (input_chars * MAX_EXPANSION);
     rval = PyString_FromStringAndSize(NULL, output_size);

-- 
Repository URL: https://hg.python.org/cpython