diff --git a/NetworkPkg/DnsDxe/DnsDhcp.c b/NetworkPkg/DnsDxe/DnsDhcp.c
index 4607f7b633..1cc337f0cf 100644
--- a/NetworkPkg/DnsDxe/DnsDhcp.c
+++ b/NetworkPkg/DnsDxe/DnsDhcp.c
@@ -301,6 +301,8 @@ GetDns4ServerFromDhcp4 (
   Data                       = NULL;
   InterfaceInfo              = NULL;
 
+  ZeroMem ((UINT8 *) ParaList, sizeof (ParaList));
+
   ZeroMem (&MnpConfigData, sizeof (EFI_MANAGED_NETWORK_CONFIG_DATA));
   
   ZeroMem (&DnsServerInfor, sizeof (DNS4_SERVER_INFOR));
diff --git a/NetworkPkg/DnsDxe/DnsImpl.c b/NetworkPkg/DnsDxe/DnsImpl.c
index c227093986..b196d181ca 100644
--- a/NetworkPkg/DnsDxe/DnsImpl.c
+++ b/NetworkPkg/DnsDxe/DnsImpl.c
@@ -1049,6 +1049,7 @@ IsValidDnsResponse (
       continue;
     } else {
       TxString = NetbufGetByte (Packet, 0, NULL);
+      ASSERT (TxString != NULL);
       DnsHeader = (DNS_HEADER *) TxString;
       QueryName = (CHAR8 *) (TxString + sizeof (*DnsHeader));
       QuerySection = (DNS_QUERY_SECTION *) (QueryName + AsciiStrLen (QueryName) + 1);
@@ -1426,7 +1427,8 @@ DnsOnPacketReceived (
   ASSERT (Packet != NULL);
   
   RcvString = NetbufGetByte (Packet, 0, NULL);
-
+  ASSERT (RcvString != NULL);
+  
   //
   // Parse Dns Response
   //
diff --git a/NetworkPkg/HttpDxe/HttpDriver.c b/NetworkPkg/HttpDxe/HttpDriver.c
index b65607a4cb..43f42e29bf 100644
--- a/NetworkPkg/HttpDxe/HttpDriver.c
+++ b/NetworkPkg/HttpDxe/HttpDriver.c
@@ -79,7 +79,7 @@ HttpCleanService (
   IN HTTP_SERVICE     *HttpService
   )
 {
-  if (HttpService != NULL) {
+  if (HttpService == NULL) {
     return ;
   }
 
diff --git a/NetworkPkg/HttpDxe/HttpImpl.c b/NetworkPkg/HttpDxe/HttpImpl.c
index 4bd4ac884f..545fe42332 100644
--- a/NetworkPkg/HttpDxe/HttpImpl.c
+++ b/NetworkPkg/HttpDxe/HttpImpl.c
@@ -766,6 +766,10 @@ HttpResponseWorker (
   HTTP_TOKEN_WRAP               *ValueInItem;
   UINTN                         HdrLen;
 
+  if (Wrap == NULL || Wrap->HttpInstance == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+  
   HttpInstance = Wrap->HttpInstance;
   Token = Wrap->HttpToken;