Use zero address when reporting unknown peer in SMK error

This avoids potential use of uninitialized stack memory when printing
out peer address based on SMK error message that does not include the
MAC address.

src/rsn_supp/peerkey.c

@@ -634,6 +634,8 @@ static int wpa_supplicant_process_smk_error(
 
 	if (kde.mac_addr && kde.mac_addr_len >= ETH_ALEN)
 		os_memcpy(peer, kde.mac_addr, ETH_ALEN);
+	else
+		os_memset(peer, 0, ETH_ALEN);
 	os_memcpy(&error, kde.error, sizeof(error));
 	error_type = be_to_host16(error.error_type);
 	wpa_msg(sm->ctx->msg_ctx, MSG_INFO,