From 280917872027ee991416d2623fc16ff1eed48f50 Mon Sep 17 00:00:00 2001

From: Christian Heimes <christian@python.org>

Date: Tue, 15 Jan 2019 23:47:42 +0100

Subject: [PATCH] bpo-35746: Fix segfault in ssl's cert parser (GH-11569)

​

Fix a NULL pointer deref in ssl module. The cert parser did not handle CRL

distribution points with empty DP or URI correctly. A malicious or buggy

certificate can result into segfault.

​

Signed-off-by: Christian Heimes <christian@python.org>

​

https://bugs.python.org/issue35746

(cherry picked from commit a37f52436f9aa4b9292878b72f3ff1480e2606c3)

​

Co-authored-by: Christian Heimes <christian@python.org>

---

 Lib/test/talos-2019-0758.pem                  | 22 +++++++++++++++++++

 Lib/test/test_ssl.py                          | 22 +++++++++++++++++++

 .../2019-01-15-18-16-05.bpo-35746.nMSd0j.rst  |  3 +++

 Modules/_ssl.c                                |  4 ++++

 4 files changed, 51 insertions(+)

 create mode 100644 Lib/test/talos-2019-0758.pem

 create mode 100644 Misc/NEWS.d/next/Security/2019-01-15-18-16-05.bpo-35746.nMSd0j.rst

​

--- a/Lib/test/test_ssl.py

+++ b/Lib/test/test_ssl.py

@@ -287,6 +287,27 @@ class BasicSocketTests(unittest.TestCase

             }

         )

+    def test_parse_cert_CVE_2019_5010(self):

+        p = ssl._ssl._test_decode_cert(TALOS_INVALID_CRLDP)

+        if support.verbose:

+            sys.stdout.write("\n" + pprint.pformat(p) + "\n")

+        self.assertEqual(

+            p,

+            {

+                'issuer': (

+                    (('countryName', 'UK'),), (('commonName', 'cody-ca'),)),

+                'notAfter': 'Jun 14 18:00:58 2028 GMT',

+                'notBefore': 'Jun 18 18:00:58 2018 GMT',

+                'serialNumber': '02',

+                'subject': ((('countryName', 'UK'),),

+                            (('commonName',

+                              'codenomicon-vm-2.test.lal.cisco.com'),)),

+                'subjectAltName': (

+                    ('DNS', 'codenomicon-vm-2.test.lal.cisco.com'),),

+                'version': 3

+            }

+        )

+

     def test_parse_cert_CVE_2013_4238(self):

         p = ssl._ssl._test_decode_cert(NULLBYTECERT)

         if support.verbose:

--- /dev/null

+++ b/Misc/NEWS.d/next/Security/2019-01-15-18-16-05.bpo-35746.nMSd0j.rst

@@ -0,0 +1,3 @@

+[CVE-2019-5010] Fix a NULL pointer deref in ssl module. The cert parser did

+not handle CRL distribution points with empty DP or URI correctly. A

+malicious or buggy certificate can result into segfault.

​