commit f21ffff2d2bc916b70e66810b4582a604f03965f
author Alex Gaynor <alex.gaynor@gmail.com> Wed Jun 28 13:24:07 2017 -0700
committer Paul Kehrer <paul.l.kehrer@gmail.com> Wed Jun 28 15:24:07 2017 -0500
tree dde2b3e3415cb61692247cd23d14811128a50660
parent 491fd7cc5aefff8064039d073331b41a2f606a63

Fix for leaking memory in EllipticCurvePublicNumbers.public_key() (#3732)

* Test for leaking memory in EllipticCurvePublicNumbers.public_key()

* Fix the memory leak

As far as I can tell, from spelunking in the OpenSSL source (as you do), EC_KEY_set_public_key_affine_coordinates doesn't take ownership of "x" or "y". https://github.com/openssl/openssl/blob/master/crypto/ec/ecp_smpl.c#L362-L420 is the place in the source I found that actually uses "x" and "y".

* Unused imports

src/cryptography/hazmat/backends/openssl/backend.py

diff --git a/src/cryptography/hazmat/backends/openssl/backend.py b/src/cryptography/hazmat/backends/openssl/backend.py
index 5458a0f..c481c09 100644
--- a/src/cryptography/hazmat/backends/openssl/backend.py
+++ b/src/cryptography/hazmat/backends/openssl/backend.py
@@ -1465,9 +1465,9 @@
                 "Invalid EC key. Both x and y must be non-negative."
             )
 
-        res = self._lib.EC_KEY_set_public_key_affine_coordinates(
-            ctx, self._int_to_bn(x), self._int_to_bn(y)
-        )
+        x = self._ffi.gc(self._int_to_bn(x), self._lib.BN_free)
+        y = self._ffi.gc(self._int_to_bn(y), self._lib.BN_free)
+        res = self._lib.EC_KEY_set_public_key_affine_coordinates(ctx, x, y)
         if res != 1:
             self._consume_errors()
             raise ValueError("Invalid EC key.")

tests/hazmat/backends/test_openssl_memleak.py

diff --git a/tests/hazmat/backends/test_openssl_memleak.py b/tests/hazmat/backends/test_openssl_memleak.py
index 53c4137..e58090a 100644
--- a/tests/hazmat/backends/test_openssl_memleak.py
+++ b/tests/hazmat/backends/test_openssl_memleak.py
@@ -189,3 +189,22 @@
 
             cert.extensions
         """), [path])
+
+    def test_ec_public_numbers_public_key(self):
+        assert_no_memory_leaks(textwrap.dedent("""
+        def func():
+            from cryptography.hazmat.backends.openssl import backend
+            from cryptography.hazmat.primitives.asymmetric import ec
+
+            ec.EllipticCurvePublicNumbers(
+                curve=ec.SECP384R1(),
+                x=int(
+                    '10036914308591746758780165503819213553101287571902957054148542'
+                    '504671046744460374996612408381962208627004841444205030'
+                ),
+                y=int(
+                    '17337335659928075994560513699823544906448896792102247714689323'
+                    '575406618073069185107088229463828921069465902299522926'
+                )
+            ).public_key(backend)
+        """))