From bee14e9ebc8db1cfa5ead35834df9a9d02101bda Mon Sep 17 00:00:00 2001
From: Fu Siyuan <siyuan.fu@intel.com>
Date: Tue, 2 Jan 2018 13:25:59 +0800
Subject: [PATCH] NetworkPkg: Update PXE driver to check for NULL pointer
 before use it.

This patch is to fix the issue that dereferencing of "This" (EFI_LOAD_FILE_PROTOCOL)
in EfiPxeLoadFile() is happening before the NULL check.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Sriram Subramanian <sriram-s@hpe.com>
Reviewed-by: Jiaxin Wu <jiaxin.wu@intel.com>
---
 NetworkPkg/UefiPxeBcDxe/PxeBcImpl.c | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/NetworkPkg/UefiPxeBcDxe/PxeBcImpl.c b/NetworkPkg/UefiPxeBcDxe/PxeBcImpl.c
index dc77d256f8..93f3bfa5ba 100644
--- a/NetworkPkg/UefiPxeBcDxe/PxeBcImpl.c
+++ b/NetworkPkg/UefiPxeBcDxe/PxeBcImpl.c
@@ -1,7 +1,7 @@
 /** @file
   This implementation of EFI_PXE_BASE_CODE_PROTOCOL and EFI_LOAD_FILE_PROTOCOL.
 
-  Copyright (c) 2007 - 2017, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2007 - 2018, 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
@@ -2349,27 +2349,23 @@ EfiPxeLoadFile (
   EFI_STATUS                  Status;
   EFI_STATUS                  MediaStatus;
 
-  if (FilePath == NULL || !IsDevicePathEnd (FilePath)) {
+  if (This == NULL || BufferSize == NULL || FilePath == NULL || !IsDevicePathEnd (FilePath)) {
     return EFI_INVALID_PARAMETER;
   }
   
+  //
+  // Only support BootPolicy
+  //
+  if (!BootPolicy) {
+    return EFI_UNSUPPORTED;
+  }
+  
   VirtualNic = PXEBC_VIRTUAL_NIC_FROM_LOADFILE (This);
   Private    = VirtualNic->Private;
   PxeBc      = &Private->PxeBc;
   UsingIpv6  = FALSE;
   Status     = EFI_DEVICE_ERROR;
 
-  if (This == NULL || BufferSize == NULL) {
-    return EFI_INVALID_PARAMETER;
-  }
-
-  //
-  // Only support BootPolicy
-  //
-  if (!BootPolicy) {
-    return EFI_UNSUPPORTED;
-  }
-
   //
   // Check media status before PXE start
   //