EAPOL supplicant: Use os_memcmp_const() for hash/password 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: Jouni Malinen <j@w1.fi>

diff --git a/src/eapol_supp/eapol_supp_sm.c b/src/eapol_supp/eapol_supp_sm.c
index e00dea3..cf3506d 100644 (file)
--- a/src/eapol_supp/eapol_supp_sm.c
+++ b/src/eapol_supp/eapol_supp_sm.c
@@ -719,8 +719,8 @@ static void eapol_sm_processKey(struct eapol_sm *sm)
        hmac_md5(keydata.sign_key, sign_key_len,
                 sm->last_rx_key, sizeof(*hdr) + be_to_host16(hdr->length),
                 key->key_signature);
-       if (os_memcmp(orig_key_sign, key->key_signature,
-                     IEEE8021X_KEY_SIGN_LEN) != 0) {
+       if (os_memcmp_const(orig_key_sign, key->key_signature,
+                           IEEE8021X_KEY_SIGN_LEN) != 0) {
                wpa_printf(MSG_DEBUG, "EAPOL: Invalid key signature in "
                           "EAPOL-Key packet");
                os_memcpy(key->key_signature, orig_key_sign,