diff --git a/SecurityPkg/Tcg/TcgDxe/TcgDxe.c b/SecurityPkg/Tcg/TcgDxe/TcgDxe.c
index 75c6a8978f..fea59c35b6 100644
--- a/SecurityPkg/Tcg/TcgDxe/TcgDxe.c
+++ b/SecurityPkg/Tcg/TcgDxe/TcgDxe.c
@@ -1,6 +1,13 @@
 /** @file  
   This module implements TCG EFI Protocol.
-  
+ 
+Caution: This module requires additional review when modified.
+This driver will have external input - TcgDxePassThroughToTpm
+This external input must be validated carefully to avoid security issue like
+buffer overflow, integer overflow.
+
+TcgDxePassThroughToTpm() will receive untrusted input and do basic validation.
+
 Copyright (c) 2005 - 2012, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials 
 are licensed and made available under the terms and conditions of the BSD License 
@@ -384,6 +391,13 @@ TcgDxePassThroughToTpm (
 {
   TCG_DXE_DATA                      *TcgData;
 
+  if (TpmInputParameterBlock == NULL || 
+      TpmOutputParameterBlock == NULL || 
+      TpmInputParameterBlockSize == 0 ||
+      TpmOutputParameterBlockSize == 0) {
+    return EFI_INVALID_PARAMETER;
+  }
+
   TcgData = TCG_DXE_DATA_FROM_THIS (This);
 
   return TisPcExecute (
diff --git a/SecurityPkg/Tcg/TcgDxe/TisDxe.c b/SecurityPkg/Tcg/TcgDxe/TisDxe.c
index 68489d3e3f..e7e0f9e405 100644
--- a/SecurityPkg/Tcg/TcgDxe/TisDxe.c
+++ b/SecurityPkg/Tcg/TcgDxe/TisDxe.c
@@ -233,6 +233,13 @@ TisPcSendV (
       return EFI_INVALID_PARAMETER;
   }
 
+  //
+  // Check input to avoid overflow.
+  //
+  if ((UINT32) (~0)- *DataLength < (UINT32)Size) {
+    return EFI_INVALID_PARAMETER;
+  }
+
   if(*DataLength + (UINT32) Size > TPMCMDBUFLENGTH) {
     return EFI_BUFFER_TOO_SMALL;
   }
@@ -291,9 +298,16 @@ TisPcReceiveV (
 
     case 'r':
       Size = VA_ARG (*ap, UINTN);
-      if(*DataIndex + (UINT32) Size <= RespSize) {
-        break;
+      //
+      // If overflowed, which means Size is big enough for Response data. 
+      // skip this check. Copy the whole data 
+      //
+      if ((UINT32) (~0)- *DataIndex >= (UINT32)Size) {
+        if(*DataIndex + (UINT32) Size <= RespSize) {
+          break;
+        }
       }
+
       *DataFinished = TRUE;
       if (*DataIndex >= RespSize) {
         return EFI_SUCCESS;