3191d1624e
Fixes CVE-2019-5010: NULL pointer dereference using a specially crafted X509 certificate https://bugs.python.org/issue35746 Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
122 lines
5.3 KiB
Diff
122 lines
5.3 KiB
Diff
From be5de958e9052e322b0087c6dba81cdad0c3e031 Mon Sep 17 00:00:00 2001
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From: "Miss Islington (bot)"
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<31488909+miss-islington@users.noreply.github.com>
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Date: Tue, 15 Jan 2019 15:03:36 -0800
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Subject: [PATCH] bpo-35746: Fix segfault in ssl's cert parser (GH-11569)
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Fix a NULL pointer deref in ssl module. The cert parser did not handle CRL
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distribution points with empty DP or URI correctly. A malicious or buggy
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certificate can result into segfault.
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Signed-off-by: Christian Heimes <christian@python.org>
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https://bugs.python.org/issue35746
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(cherry picked from commit a37f52436f9aa4b9292878b72f3ff1480e2606c3)
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Co-authored-by: Christian Heimes <christian@python.org>
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Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
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---
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Lib/test/talos-2019-0758.pem | 22 ++++++++++++++++++++++
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Lib/test/test_ssl.py | 22 ++++++++++++++++++++++
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.../2019-01-15-18-16-05.bpo-35746.nMSd0j.rst | 3 +++
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Modules/_ssl.c | 4 ++++
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4 files changed, 51 insertions(+)
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create mode 100644 Lib/test/talos-2019-0758.pem
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create mode 100644 Misc/NEWS.d/next/Security/2019-01-15-18-16-05.bpo-35746.nMSd0j.rst
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diff --git a/Lib/test/talos-2019-0758.pem b/Lib/test/talos-2019-0758.pem
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new file mode 100644
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index 0000000000..13b95a77fd
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--- /dev/null
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+++ b/Lib/test/talos-2019-0758.pem
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@@ -0,0 +1,22 @@
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+-----BEGIN CERTIFICATE-----
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+MIIDqDCCApKgAwIBAgIBAjALBgkqhkiG9w0BAQswHzELMAkGA1UEBhMCVUsxEDAO
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+BgNVBAMTB2NvZHktY2EwHhcNMTgwNjE4MTgwMDU4WhcNMjgwNjE0MTgwMDU4WjA7
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+MQswCQYDVQQGEwJVSzEsMCoGA1UEAxMjY29kZW5vbWljb24tdm0tMi50ZXN0Lmxh
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+bC5jaXNjby5jb20wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQC63fGB
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+J80A9Av1GB0bptslKRIUtJm8EeEu34HkDWbL6AJY0P8WfDtlXjlPaLqFa6sqH6ES
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+V48prSm1ZUbDSVL8R6BYVYpOlK8/48xk4pGTgRzv69gf5SGtQLwHy8UPBKgjSZoD
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+5a5k5wJXGswhKFFNqyyxqCvWmMnJWxXTt2XDCiWc4g4YAWi4O4+6SeeHVAV9rV7C
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+1wxqjzKovVe2uZOHjKEzJbbIU6JBPb6TRfMdRdYOw98n1VXDcKVgdX2DuuqjCzHP
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+WhU4Tw050M9NaK3eXp4Mh69VuiKoBGOLSOcS8reqHIU46Reg0hqeL8LIL6OhFHIF
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+j7HR6V1X6F+BfRS/AgMBAAGjgdYwgdMwCQYDVR0TBAIwADAdBgNVHQ4EFgQUOktp
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+HQjxDXXUg8prleY9jeLKeQ4wTwYDVR0jBEgwRoAUx6zgPygZ0ZErF9sPC4+5e2Io
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+UU+hI6QhMB8xCzAJBgNVBAYTAlVLMRAwDgYDVQQDEwdjb2R5LWNhggkA1QEAuwb7
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+2s0wCQYDVR0SBAIwADAuBgNVHREEJzAlgiNjb2Rlbm9taWNvbi12bS0yLnRlc3Qu
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+bGFsLmNpc2NvLmNvbTAOBgNVHQ8BAf8EBAMCBaAwCwYDVR0fBAQwAjAAMAsGCSqG
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+SIb3DQEBCwOCAQEAvqantx2yBlM11RoFiCfi+AfSblXPdrIrHvccepV4pYc/yO6p
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+t1f2dxHQb8rWH3i6cWag/EgIZx+HJQvo0rgPY1BFJsX1WnYf1/znZpkUBGbVmlJr
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+t/dW1gSkNS6sPsM0Q+7HPgEv8CPDNK5eo7vU2seE0iWOkxSyVUuiCEY9ZVGaLVit
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+p0C78nZ35Pdv4I+1cosmHl28+es1WI22rrnmdBpH8J1eY6WvUw2xuZHLeNVN0TzV
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+Q3qq53AaCWuLOD1AjESWuUCxMZTK9DPS4JKXTK8RLyDeqOvJGjsSWp3kL0y3GaQ+
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+10T1rfkKJub2+m9A9duin1fn6tHc2wSvB7m3DA==
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+-----END CERTIFICATE-----
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diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
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index f1b9565c8d..b6794ce3a8 100644
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--- a/Lib/test/test_ssl.py
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+++ b/Lib/test/test_ssl.py
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@@ -116,6 +116,7 @@ NONEXISTINGCERT = data_file("XXXnonexisting.pem")
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BADKEY = data_file("badkey.pem")
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NOKIACERT = data_file("nokia.pem")
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NULLBYTECERT = data_file("nullbytecert.pem")
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+TALOS_INVALID_CRLDP = data_file("talos-2019-0758.pem")
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DHFILE = data_file("ffdh3072.pem")
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BYTES_DHFILE = os.fsencode(DHFILE)
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@@ -365,6 +366,27 @@ class BasicSocketTests(unittest.TestCase):
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self.assertEqual(p['crlDistributionPoints'],
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('http://SVRIntl-G3-crl.verisign.com/SVRIntlG3.crl',))
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+ def test_parse_cert_CVE_2019_5010(self):
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+ p = ssl._ssl._test_decode_cert(TALOS_INVALID_CRLDP)
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+ if support.verbose:
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+ sys.stdout.write("\n" + pprint.pformat(p) + "\n")
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+ self.assertEqual(
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+ p,
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+ {
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+ 'issuer': (
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+ (('countryName', 'UK'),), (('commonName', 'cody-ca'),)),
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+ 'notAfter': 'Jun 14 18:00:58 2028 GMT',
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+ 'notBefore': 'Jun 18 18:00:58 2018 GMT',
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+ 'serialNumber': '02',
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+ 'subject': ((('countryName', 'UK'),),
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+ (('commonName',
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+ 'codenomicon-vm-2.test.lal.cisco.com'),)),
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+ 'subjectAltName': (
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+ ('DNS', 'codenomicon-vm-2.test.lal.cisco.com'),),
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+ 'version': 3
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+ }
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+ )
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+
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def test_parse_cert_CVE_2013_4238(self):
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p = ssl._ssl._test_decode_cert(NULLBYTECERT)
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if support.verbose:
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diff --git a/Misc/NEWS.d/next/Security/2019-01-15-18-16-05.bpo-35746.nMSd0j.rst b/Misc/NEWS.d/next/Security/2019-01-15-18-16-05.bpo-35746.nMSd0j.rst
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new file mode 100644
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index 0000000000..dffe347eec
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--- /dev/null
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+++ b/Misc/NEWS.d/next/Security/2019-01-15-18-16-05.bpo-35746.nMSd0j.rst
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@@ -0,0 +1,3 @@
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+[CVE-2019-5010] Fix a NULL pointer deref in ssl module. The cert parser did
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+not handle CRL distribution points with empty DP or URI correctly. A
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+malicious or buggy certificate can result into segfault.
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diff --git a/Modules/_ssl.c b/Modules/_ssl.c
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index 9894ad821d..9baec8a9bc 100644
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--- a/Modules/_ssl.c
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+++ b/Modules/_ssl.c
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@@ -1516,6 +1516,10 @@ _get_crl_dp(X509 *certificate) {
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STACK_OF(GENERAL_NAME) *gns;
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dp = sk_DIST_POINT_value(dps, i);
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+ if (dp->distpoint == NULL) {
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+ /* Ignore empty DP value, CVE-2019-5010 */
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+ continue;
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+ }
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gns = dp->distpoint->name.fullname;
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for (j=0; j < sk_GENERAL_NAME_num(gns); j++) {
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--
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2.11.0
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