PR: 2743
Reported by: Dmitry Belyavsky <beldmit@gmail.com>

Fix memory leak if invalid GOST MAC key given.

engines/ccgost/gost_pmeth.c

diff --git a/engines/ccgost/gost_pmeth.c b/engines/ccgost/gost_pmeth.c
index 4a05853..0bd08e9 100644
--- a/engines/ccgost/gost_pmeth.c
+++ b/engines/ccgost/gost_pmeth.c
@@ -521,6 +521,7 @@
 				{
 				GOSTerr(GOST_F_PKEY_GOST_MAC_CTRL_STR,
 					GOST_R_INVALID_MAC_KEY_LENGTH);
+				OPENSSL_free(keybuf);
 				return 0;	
 				}
 			ret= pkey_gost_mac_ctrl(ctx, EVP_PKEY_CTRL_SET_MAC_KEY,