Add missing ForceZero calls

Author: Frauschi

src/keys.c

@@ -3948,6 +3948,17 @@ int DeriveKeys(WOLFSSL* ssl)
             ret = StoreKeys(ssl, keyData, PROVISION_CLIENT_SERVER);
     }
 
+    ForceZero(shaOutput, WC_SHA_DIGEST_SIZE);
+    ForceZero(md5Input, SECRET_LEN + WC_SHA_DIGEST_SIZE);
+    ForceZero(shaInput, KEY_PREFIX + SECRET_LEN + 2 * RAN_LEN);
+    ForceZero(keyData, KEY_PREFIX * WC_MD5_DIGEST_SIZE);
+#ifdef WOLFSSL_CHECK_MEM_ZERO
+    wc_MemZero_Check(shaOutput, WC_SHA_DIGEST_SIZE);
+    wc_MemZero_Check(md5Input, SECRET_LEN + WC_SHA_DIGEST_SIZE);
+    wc_MemZero_Check(shaInput, KEY_PREFIX + SECRET_LEN + 2 * RAN_LEN);
+    wc_MemZero_Check(keyData, KEY_PREFIX * WC_MD5_DIGEST_SIZE);
+#endif
+
     WC_FREE_VAR_EX(shaOutput, NULL, DYNAMIC_TYPE_TMP_BUFFER);
     WC_FREE_VAR_EX(md5Input, NULL, DYNAMIC_TYPE_TMP_BUFFER);
     WC_FREE_VAR_EX(shaInput, NULL, DYNAMIC_TYPE_TMP_BUFFER);
@@ -3963,16 +3974,20 @@ static int CleanPreMaster(WOLFSSL* ssl)
 {
     int i, ret, sz = (int)(ssl->arrays->preMasterSz);
 
-    for (i = 0; i < sz; i++)
-        ssl->arrays->preMasterSecret[i] = 0;
+    ForceZero(ssl->arrays->preMasterSecret, sz);
+#ifdef WOLFSSL_CHECK_MEM_ZERO
+    wc_MemZero_Check(ssl->arrays->preMasterSecret, sz);
+#endif
 
     ret = wc_RNG_GenerateBlock(ssl->rng, ssl->arrays->preMasterSecret,
                                                             (word32)(sz));
     if (ret != 0)
         return ret;
 
-    for (i = 0; i < sz; i++)
-        ssl->arrays->preMasterSecret[i] = 0;
+    ForceZero(ssl->arrays->preMasterSecret, sz);
+#ifdef WOLFSSL_CHECK_MEM_ZERO
+    wc_MemZero_Check(ssl->arrays->preMasterSecret, sz);
+#endif
 
     XFREE(ssl->arrays->preMasterSecret, ssl->heap, DYNAMIC_TYPE_SECRET);
     ssl->arrays->preMasterSecret = NULL;
@@ -4096,6 +4111,13 @@ static int MakeSslMasterSecret(WOLFSSL* ssl)
             ret = DeriveKeys(ssl);
     }
 
+    ForceZero(md5Input, ENCRYPT_LEN + WC_SHA_DIGEST_SIZE);
+    ForceZero(shaInput, PREFIX + ENCRYPT_LEN + 2 * RAN_LEN);
+#ifdef WOLFSSL_CHECK_MEM_ZERO
+    wc_MemZero_Check(md5Input, ENCRYPT_LEN + WC_SHA_DIGEST_SIZE);
+    wc_MemZero_Check(shaInput, PREFIX + ENCRYPT_LEN + 2 * RAN_LEN);
+#endif
+
     WC_FREE_VAR_EX(shaOutput, NULL, DYNAMIC_TYPE_TMP_BUFFER);
     WC_FREE_VAR_EX(md5Input, NULL, DYNAMIC_TYPE_TMP_BUFFER);
     WC_FREE_VAR_EX(shaInput, NULL, DYNAMIC_TYPE_TMP_BUFFER);

src/tls.c

@@ -488,6 +488,11 @@ int DeriveTlsKeys(WOLFSSL* ssl)
     if (ret == 0)
         ret = StoreKeys(ssl, key_dig, PROVISION_CLIENT_SERVER);
 
+    ForceZero(key_dig, MAX_PRF_DIG);
+#ifdef WOLFSSL_CHECK_MEM_ZERO
+    wc_MemZero_Check(key_dig, MAX_PRF_DIG);
+#endif
+
     WC_FREE_VAR_EX(key_dig, ssl->heap, DYNAMIC_TYPE_DIGEST);
 
     return ret;

src/tls13.c

@@ -1208,7 +1208,7 @@ int DeriveHandshakeSecret(WOLFSSL* ssl)
                         derivedLabel, DERIVED_LABEL_SZ,
                         NULL, 0, ssl->specs.mac_algorithm);
     if (ret != 0)
-        return ret;
+        goto end;
 
     PRIVATE_KEY_UNLOCK();
     ret = Tls13_HKDF_Extract(ssl, ssl->arrays->preMasterSecret,
@@ -1217,6 +1217,11 @@ int DeriveHandshakeSecret(WOLFSSL* ssl)
             mac2hash(ssl->specs.mac_algorithm));
     PRIVATE_KEY_LOCK();
 
+end:
+    ForceZero(key, sizeof(key));
+#ifdef WOLFSSL_CHECK_MEM_ZERO
+    wc_MemZero_Check(key, sizeof(key));
+#endif
     return ret;
 }
 
@@ -1244,14 +1249,19 @@ int DeriveMasterSecret(WOLFSSL* ssl)
     ret = DeriveKeyMsg(ssl, key, -1, ssl->arrays->preMasterSecret,
                         derivedLabel, DERIVED_LABEL_SZ,
                         NULL, 0, ssl->specs.mac_algorithm);
-    if (ret != 0)
-        return ret;
+    if (ret == 0) {
+        PRIVATE_KEY_UNLOCK();
+        ret = Tls13_HKDF_Extract(ssl, ssl->arrays->masterSecret,
+                                 key, ssl->specs.hash_size,
+                                 ssl->arrays->masterSecret, 0,
+                                 mac2hash(ssl->specs.mac_algorithm));
+        PRIVATE_KEY_LOCK();
+    }
 
-    PRIVATE_KEY_UNLOCK();
-    ret = Tls13_HKDF_Extract(ssl, ssl->arrays->masterSecret,
-            key, ssl->specs.hash_size,
-            ssl->arrays->masterSecret, 0, mac2hash(ssl->specs.mac_algorithm));
-    PRIVATE_KEY_LOCK();
+    ForceZero(key, sizeof(key));
+#ifdef WOLFSSL_CHECK_MEM_ZERO
+    wc_MemZero_Check(key, sizeof(key));
+#endif
 
 #ifdef HAVE_KEYING_MATERIAL
     if (ret != 0)