crypto: gcm - Filter out async ghash if necessary

BugLink: http://bugs.launchpad.net/bugs/1614560

commit b30bdfa8 upstream.

As it is if you ask for a sync gcm you may actually end up with
an async one because it does not filter out async implementations
of ghash.

This patch fixes this by adding the necessary filter when looking
for ghash.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

crypto/gcm.c

@@ -639,7 +639,9 @@ static int crypto_gcm_create_common(struct crypto_template *tmpl,
 
 	ghash_alg = crypto_find_alg(ghash_name, &crypto_ahash_type,
 				    CRYPTO_ALG_TYPE_HASH,
-				    CRYPTO_ALG_TYPE_AHASH_MASK);
+				    CRYPTO_ALG_TYPE_AHASH_MASK |
+				    crypto_requires_sync(algt->type,
+							 algt->mask));
 	if (IS_ERR(ghash_alg))
 		return PTR_ERR(ghash_alg);