Fix CVE-2023-49083: NULL-dereference when loading PKCS7 certificates

resolves: RHEL-19830

0008-CVE-2023-49083.patch

@@ -0,0 +1,45 @@
+From 66cb448876b1e95b637461d13560b970bae09e08 Mon Sep 17 00:00:00 2001
+From: Alex Gaynor <alex.gaynor@gmail.com>
+Date: Wed, 22 Nov 2023 16:49:56 -0500
+Subject: [PATCH] Fixed crash when loading a PKCS#7 bundle with no certificates
+
+---
+ src/cryptography/hazmat/backends/openssl/backend.py | 5 ++++-
+ tests/hazmat/primitives/test_pkcs7.py               | 6 ++++++
+ 2 files changed, 10 insertions(+), 1 deletion(-)
+
+diff --git a/src/cryptography/hazmat/backends/openssl/backend.py b/src/cryptography/hazmat/backends/openssl/backend.py
+index 7c08862b307..adfd7aefe5f 100644
+--- a/src/cryptography/hazmat/backends/openssl/backend.py
++++ b/src/cryptography/hazmat/backends/openssl/backend.py
+@@ -1111,9 +1111,12 @@ def _load_pkcs7_certificates(self, p7) -> list[x509.Certificate]:
+                 _Reasons.UNSUPPORTED_SERIALIZATION,
+             )
+ 
++        certs: list[x509.Certificate] = []
++        if p7.d.sign == self._ffi.NULL:
++            return certs
++
+         sk_x509 = p7.d.sign.cert
+         num = self._lib.sk_X509_num(sk_x509)
+-        certs = []
+         for i in range(num):
+             x509 = self._lib.sk_X509_value(sk_x509, i)
+             self.openssl_assert(x509 != self._ffi.NULL)
+diff --git a/tests/hazmat/primitives/test_pkcs7.py b/tests/hazmat/primitives/test_pkcs7.py
+index ceb84e5fb48..434a361057f 100644
+--- a/tests/hazmat/primitives/test_pkcs7.py
++++ b/tests/hazmat/primitives/test_pkcs7.py
+@@ -89,6 +89,12 @@ def test_load_pkcs7_unsupported_type(self, backend):
+                 mode="rb",
+             )
+ 
++    def test_load_pkcs7_empty_certificates(self):
++        der = b"\x30\x0B\x06\x09\x2A\x86\x48\x86\xF7\x0D\x01\x07\x02"
++
++        certificates = pkcs7.load_der_pkcs7_certificates(der)
++        assert certificates == []
++
+ 
+ # We have no public verification API and won't be adding one until we get
+ # some requirements from users so this function exists to give us basic

python-cryptography.spec

@@ -7,7 +7,7 @@
 
 Name:           python-%{srcname}
 Version:        36.0.1
-Release:        4%{?dist}
+Release:        5%{?dist}
 Summary:        PyCA's cryptography library
 
 License:        ASL 2.0 or BSD
@@ -25,6 +25,7 @@ Patch5:		0005-Fixed-serialization-of-keyusage-ext-with-no-bits-693.patch
 # https://github.com/pyca/cryptography/pull/8230
 Patch6:		0006-CVE-2023-23931.patch
 Patch7:		0007-Adapt-for-OpenSSL-RSA-bleichenbacher-mitigation-7895.patch
+Patch8:		0008-CVE-2023-49083.patch
 
 ExclusiveArch:  %{rust_arches}
 
@@ -129,6 +130,10 @@ PYTHONPATH=${PWD}/vectors:%{buildroot}%{python3_sitearch} \
 %{python3_sitearch}/%{srcname}-%{version}-py*.egg-info
 
 %changelog
+* Thu Jan 04 2024 Christian Heimes <cheimes@redhat.com> - 36.0.1-5
+- Fix CVE-2023-49083: NULL-dereference when loading PKCS7 certificates,
+  resolves RHEL-19830
+
 * Mon May 15 2023 Christian Heimes <cheimes@redhat.com> - 36.0.1-4
 - Fix FTBFS caused by rsa_pkcs1_implicit_rejection OpenSSL feature, resolves rhbz#2203840