Date: Thu, 15 Oct 2020 16:22:12 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Postgres hackers <pgsql-hackers@lists.postgresql.org>
Subject: Possible memory leak in pgcrypto with EVP_MD_CTX
Message-ID: <20201015072212.GC2305@paquier.xyz>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
	protocol="application/pgp-signature"; boundary="vmttodhTwj0NAgWp"
Content-Disposition: inline
Precedence: bulk


--vmttodhTwj0NAgWp
Content-Type: multipart/mixed; boundary="g7w8+K/95kPelPD2"
Content-Disposition: inline


--g7w8+K/95kPelPD2
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline

Hi all,

It happens that pgcrypto has the following leak if a digest cannot be
initialized:
--- a/contrib/pgcrypto/openssl.c
+++ b/contrib/pgcrypto/openssl.c
@@ -202,6 +202,7 @@ px_find_digest(const char *name, PX_MD **res)
    }
    if (EVP_DigestInit_ex(ctx, md, NULL) == 0)
    {
+       EVP_MD_CTX_destroy(ctx);
        pfree(digest);
        return -1;
    }

That's a bit annoying, because this memory is allocated directly by
OpenSSL, and Postgres does not know how to free it until it gets
registered in the list of open_digests that would be used by the
cleanup callback, so I think that we had better back-patch this fix.

Thoughts?
--
Michael

--g7w8+K/95kPelPD2
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment; filename="pgcrypto-leak.patch"

diff --git a/contrib/pgcrypto/openssl.c b/contrib/pgcrypto/openssl.c
index 90951a8ae7..ed96e4ce53 100644
--- a/contrib/pgcrypto/openssl.c
+++ b/contrib/pgcrypto/openssl.c
@@ -202,6 +202,7 @@ px_find_digest(const char *name, PX_MD **res)
 	}
 	if (EVP_DigestInit_ex(ctx, md, NULL) == 0)
 	{
+		EVP_MD_CTX_destroy(ctx);
 		pfree(digest);
 		return -1;
 	}

--g7w8+K/95kPelPD2--

--vmttodhTwj0NAgWp
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=Qg/p
-----END PGP SIGNATURE-----

--vmttodhTwj0NAgWp--