[Bug 334236] double free in PK11_ListPrivKeysInSlot if keys allocation fails. r=nelson

security/nss/lib/pk11wrap/pk11akey.c

@@ -2013,6 +2013,7 @@ PK11_ListPrivKeysInSlot(PK11SlotInfo *slot, char *nickname, void *wincx)
     keys = SECKEY_NewPrivateKeyList();
     if (keys == NULL) {
 	PORT_Free(key_ids);
+	return NULL;
     }
 
     for (i=0; i < objCount ; i++) {