Only set CMS parameter when encrypting

Reviewed-by: NRich Salz <rsalz@openssl.org>

crypto/cms/cms_enc.c

@@ -175,21 +175,22 @@ BIO *cms_EncryptedContent_init_bio(CMS_EncryptedContentInfo *ec)
                CMS_R_CIPHER_INITIALISATION_ERROR);
         goto err;
     }
-
-    calg->parameter = ASN1_TYPE_new();
-    if (calg->parameter == NULL) {
-        CMSerr(CMS_F_CMS_ENCRYPTEDCONTENT_INIT_BIO, ERR_R_MALLOC_FAILURE);
-        goto err;
-    }
-    if (EVP_CIPHER_param_to_asn1(ctx, calg->parameter) <= 0) {
-        CMSerr(CMS_F_CMS_ENCRYPTEDCONTENT_INIT_BIO,
-               CMS_R_CIPHER_PARAMETER_INITIALISATION_ERROR);
-        goto err;
-    }
-    /* If parameter type not set omit parameter */
-    if (calg->parameter->type == V_ASN1_UNDEF) {
-        ASN1_TYPE_free(calg->parameter);
-        calg->parameter = NULL;
+    if (enc) {
+        calg->parameter = ASN1_TYPE_new();
+        if (calg->parameter == NULL) {
+            CMSerr(CMS_F_CMS_ENCRYPTEDCONTENT_INIT_BIO, ERR_R_MALLOC_FAILURE);
+            goto err;
+        }
+        if (EVP_CIPHER_param_to_asn1(ctx, calg->parameter) <= 0) {
+            CMSerr(CMS_F_CMS_ENCRYPTEDCONTENT_INIT_BIO,
+                   CMS_R_CIPHER_PARAMETER_INITIALISATION_ERROR);
+            goto err;
+        }
+        /* If parameter type not set omit parameter */
+        if (calg->parameter->type == V_ASN1_UNDEF) {
+            ASN1_TYPE_free(calg->parameter);
+            calg->parameter = NULL;
+        }
     }
     ok = 1;