From 94020bb40f12a9057aed2dfaa89ad35d644d704e Mon Sep 17 00:00:00 2001
From: rsun3 <rsun3@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Wed, 14 Mar 2012 03:17:17 +0000
Subject: Improve robustness when scanning PCI Option ROM.

Signed-off-by: rsun3
Reviewed-by: geekboy15a


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13095 6f19259b-4bc3-4df7-8a09-765794883524
---
 OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c | 36 +++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 8 deletions(-)

(limited to 'OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c')

diff --git a/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c b/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c
index b0d045df9b..58531a800b 100644
--- a/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c
+++ b/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c
@@ -1,7 +1,7 @@
 /** @file
   Platform BDS customizations.
 
-  Copyright (c) 2004 - 2009, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2004 - 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
   which accompanies this distribution.  The full text of the license may be found at
@@ -1489,6 +1489,7 @@ PciRomLoadEfiDriversFromRomImage (
   VOID                          *DecompressedImageBuffer;
   UINT32                        ImageLength;
   EFI_DECOMPRESS_PROTOCOL       *Decompress;
+  UINT32                        InitializationSize;
 
   FileName = L"PciRomInMemory";
 
@@ -1503,24 +1504,43 @@ PciRomLoadEfiDriversFromRomImage (
 
     EfiRomHeader = (EFI_PCI_EXPANSION_ROM_HEADER *) (UINTN) RomOffset;
 
-    if (EfiRomHeader->Signature != 0xaa55) {
+    if (EfiRomHeader->Signature != PCI_EXPANSION_ROM_HEADER_SIGNATURE) {
       return retStatus;
     }
 
+    //
+    // If the pointer to the PCI Data Structure is invalid, no further images can be located. 
+    // The PCI Data Structure must be DWORD aligned. 
+    //
+    if (EfiRomHeader->PcirOffset == 0 ||
+        (EfiRomHeader->PcirOffset & 3) != 0 ||
+        RomOffset - (UINTN)Rom + EfiRomHeader->PcirOffset + sizeof (PCI_DATA_STRUCTURE) > RomSize) {
+      break;
+    }
     Pcir      = (PCI_DATA_STRUCTURE *) (UINTN) (RomOffset + EfiRomHeader->PcirOffset);
+    //
+    // If a valid signature is not present in the PCI Data Structure, no further images can be located.
+    //
+    if (Pcir->Signature != PCI_DATA_STRUCTURE_SIGNATURE) {
+      break;
+    }
     ImageSize = Pcir->ImageLength * 512;
+    if (RomOffset - (UINTN)Rom + ImageSize > RomSize) {
+      break;
+    }
 
     if ((Pcir->CodeType == PCI_CODE_TYPE_EFI_IMAGE) &&
-        (EfiRomHeader->EfiSignature == EFI_PCI_EXPANSION_ROM_HEADER_EFISIGNATURE) ) {
+        (EfiRomHeader->EfiSignature == EFI_PCI_EXPANSION_ROM_HEADER_EFISIGNATURE) &&
+        ((EfiRomHeader->EfiSubsystem == EFI_IMAGE_SUBSYSTEM_EFI_BOOT_SERVICE_DRIVER) ||
+         (EfiRomHeader->EfiSubsystem == EFI_IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER))) {
 
-      if ((EfiRomHeader->EfiSubsystem == EFI_IMAGE_SUBSYSTEM_EFI_BOOT_SERVICE_DRIVER) ||
-          (EfiRomHeader->EfiSubsystem == EFI_IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER) ) {
+      ImageOffset             = EfiRomHeader->EfiImageHeaderOffset;
+      InitializationSize      = EfiRomHeader->InitializationSize * 512;
 
-        ImageOffset             = EfiRomHeader->EfiImageHeaderOffset;
-        ImageSize               = EfiRomHeader->InitializationSize * 512;
+      if (InitializationSize <= ImageSize && ImageOffset < InitializationSize) {
 
         ImageBuffer             = (VOID *) (UINTN) (RomOffset + ImageOffset);
-        ImageLength             = ImageSize - ImageOffset;
+        ImageLength             = InitializationSize - ImageOffset;
         DecompressedImageBuffer = NULL;
 
         //
-- 
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