EAP-pwd: Use os_memcmp_const() for hash comparisons

This makes the implementation less likely to provide useful timing
information to potential attackers from comparisons of information
received from a remote device and private material known only by the
authorized devices.

Signed-off-by: Florent Daigniere <nextgens@freenetproject.org>

src/eap_peer/eap_pwd.c

@@ -589,7 +589,7 @@ eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
 	eap_pwd_h_final(hash, conf);
 
 	ptr = (u8 *) payload;
-	if (os_memcmp(conf, ptr, SHA256_MAC_LEN)) {
+	if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
 		wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm did not verify");
 		goto fin;
 	}

src/eap_server/eap_server_pwd.c

@@ -835,7 +835,7 @@ eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
 	eap_pwd_h_final(hash, conf);
 
 	ptr = (u8 *) payload;
-	if (os_memcmp(conf, ptr, SHA256_MAC_LEN)) {
+	if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
 		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
 			   "verify");
 		goto fin;