SAE: Check hmac_sha256() result in sae_token_hash()

In theory, hmac_sha256() might fail, so check for that possibility
instead of continuing with undetermined index value that could point to
an arbitrary token entry.

Signed-off-by: Jouni Malinen <j@w1.fi>

diff --git a/src/ap/ieee802_11.c b/src/ap/ieee802_11.c
index 89c15b8e62763723da8fdef1ab6a1fb9e6dc81d6..e3daee2c980f9605fbe529ed768036bd88443bf6 100644 (file)
--- a/src/ap/ieee802_11.c
+++ b/src/ap/ieee802_11.c
@@ -639,13 +639,15 @@ static int use_sae_anti_clogging(struct hostapd_data *hapd)
 }
 
 
-static u8 sae_token_hash(struct hostapd_data *hapd, const u8 *addr)
+static int sae_token_hash(struct hostapd_data *hapd, const u8 *addr, u8 *idx)
 {
        u8 hash[SHA256_MAC_LEN];
 
-       hmac_sha256(hapd->sae_token_key, sizeof(hapd->sae_token_key),
-                   addr, ETH_ALEN, hash);
-       return hash[0];
+       if (hmac_sha256(hapd->sae_token_key, sizeof(hapd->sae_token_key),
+                       addr, ETH_ALEN, hash) < 0)
+               return -1;
+       *idx = hash[0];
+       return 0;
 }
 
 
@@ -658,9 +660,8 @@ static int check_sae_token(struct hostapd_data *hapd, const u8 *addr,
        u16 token_idx;
        u8 idx;
 
-       if (token_len != SHA256_MAC_LEN)
+       if (token_len != SHA256_MAC_LEN || sae_token_hash(hapd, addr, &idx) < 0)
                return -1;
-       idx = sae_token_hash(hapd, addr);
        token_idx = hapd->sae_pending_token_idx[idx];
        if (token_idx == 0 || token_idx != WPA_GET_BE16(token)) {
                wpa_printf(MSG_DEBUG, "SAE: Invalid anti-clogging token from "
@@ -724,7 +725,10 @@ static struct wpabuf * auth_build_token_req(struct hostapd_data *hapd,
                wpabuf_put_u8(buf, WLAN_EID_EXT_ANTI_CLOGGING_TOKEN);
        }
 
-       p_idx = sae_token_hash(hapd, addr);
+       if (sae_token_hash(hapd, addr, &p_idx) < 0) {
+               wpabuf_free(buf);
+               return NULL;
+       }
        token_idx = hapd->sae_pending_token_idx[p_idx];
        if (!token_idx) {
                hapd->sae_token_idx++;