fix a memory leak in AIA parsing (#4836)

* fix a memory leak in AIA parsing

* oops can't remove that

3 files changed, 31 insertions, 2 deletions

diff --git a/src/_cffi_src/openssl/x509v3.py b/src/_cffi_src/openssl/x509v3.py
index 193d2e23..59681206 100644
--- a/src/_cffi_src/openssl/x509v3.py
+++ b/src/_cffi_src/openssl/x509v3.py
@@ -177,6 +177,7 @@ typedef struct {
 typedef void (*sk_GENERAL_NAME_freefunc)(GENERAL_NAME *);
 typedef void (*sk_DIST_POINT_freefunc)(DIST_POINT *);
 typedef void (*sk_POLICYINFO_freefunc)(POLICYINFO *);
+typedef void (*sk_ACCESS_DESCRIPTION_freefunc)(ACCESS_DESCRIPTION *);
 """
 
 
@@ -228,6 +229,8 @@ ACCESS_DESCRIPTION *sk_ACCESS_DESCRIPTION_value(
     Cryptography_STACK_OF_ACCESS_DESCRIPTION *, int
 );
 void sk_ACCESS_DESCRIPTION_free(Cryptography_STACK_OF_ACCESS_DESCRIPTION *);
+void sk_ACCESS_DESCRIPTION_pop_free(Cryptography_STACK_OF_ACCESS_DESCRIPTION *,
+                              sk_ACCESS_DESCRIPTION_freefunc);
 int sk_ACCESS_DESCRIPTION_push(Cryptography_STACK_OF_ACCESS_DESCRIPTION *,
                                ACCESS_DESCRIPTION *);
 
diff --git a/src/cryptography/hazmat/backends/openssl/decode_asn1.py b/src/cryptography/hazmat/backends/openssl/decode_asn1.py
index 773189d4..75d5844b 100644
--- a/src/cryptography/hazmat/backends/openssl/decode_asn1.py
+++ b/src/cryptography/hazmat/backends/openssl/decode_asn1.py
@@ -379,7 +379,14 @@ def _decode_authority_key_identifier(backend, akid):
 
 def _decode_authority_information_access(backend, aia):
     aia = backend._ffi.cast("Cryptography_STACK_OF_ACCESS_DESCRIPTION *", aia)
-    aia = backend._ffi.gc(aia, backend._lib.sk_ACCESS_DESCRIPTION_free)
+    aia = backend._ffi.gc(
+        aia,
+        lambda x: backend._lib.sk_ACCESS_DESCRIPTION_pop_free(
+            x, backend._ffi.addressof(
+                backend._lib._original_lib, "ACCESS_DESCRIPTION_free"
+            )
+        )
+    )
     num = backend._lib.sk_ACCESS_DESCRIPTION_num(aia)
     access_descriptions = []
     for i in range(num):
diff --git a/tests/hazmat/backends/test_openssl_memleak.py b/tests/hazmat/backends/test_openssl_memleak.py
index ed22b5db..f9ae1c46 100644
--- a/tests/hazmat/backends/test_openssl_memleak.py
+++ b/tests/hazmat/backends/test_openssl_memleak.py
@@ -210,7 +210,7 @@ class TestOpenSSLMemoryLeaks(object):
     @pytest.mark.parametrize("path", [
         "x509/PKITS_data/certs/ValidcRLIssuerTest28EE.crt",
     ])
-    def test_x509_certificate_extensions(self, path):
+    def test_der_x509_certificate_extensions(self, path):
         assert_no_memory_leaks(textwrap.dedent("""
         def func(path):
             from cryptography import x509
@@ -226,6 +226,25 @@ class TestOpenSSLMemoryLeaks(object):
             cert.extensions
         """), [path])
 
+    @pytest.mark.parametrize("path", [
+        "x509/cryptography.io.pem",
+    ])
+    def test_pem_x509_certificate_extensions(self, path):
+        assert_no_memory_leaks(textwrap.dedent("""
+        def func(path):
+            from cryptography import x509
+            from cryptography.hazmat.backends.openssl import backend
+
+            import cryptography_vectors
+
+            with cryptography_vectors.open_vector_file(path, "rb") as f:
+                cert = x509.load_pem_x509_certificate(
+                    f.read(), backend
+                )
+
+            cert.extensions
+        """), [path])
+
     def test_x509_csr_extensions(self):
         assert_no_memory_leaks(textwrap.dedent("""
         def func():