From 55501e13510038786f735a681c43a3354b363355 Mon Sep 17 00:00:00 2001 From: Eric Dong Date: Wed, 15 Oct 2014 05:17:41 +0000 Subject: =?UTF-8?q?Prevent=20EBDA=20area=20being=20overwritten,=20get=20th?= =?UTF-8?q?e=20size=20info=20from=20the=20address=200x40E.=20If=20can?= =?UTF-8?q?=E2=80=99t=20get=20the=20size=20info,=20then=20use=20the=20defa?= =?UTF-8?q?ult=20value=20for=20it.?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Eric Dong Reviewed-by: Ruiyu Ni git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16216 6f19259b-4bc3-4df7-8a09-765794883524 --- DuetPkg/DxeIpl/HobGeneration.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/DuetPkg/DxeIpl/HobGeneration.c b/DuetPkg/DxeIpl/HobGeneration.c index 401d5c718d..fac74b08fd 100644 --- a/DuetPkg/DxeIpl/HobGeneration.c +++ b/DuetPkg/DxeIpl/HobGeneration.c @@ -1,6 +1,6 @@ /** @file -Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.
+Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.
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 @@ -25,6 +25,7 @@ Revision History: #define EFI_CPUID_EXTENDED_FUNCTION 0x80000000 #define CPUID_EXTENDED_ADD_SIZE 0x80000008 +#define EBDA_VALUE_ADDRESS 0x40E HOB_TEMPLATE gHobTemplate = { { // Phit @@ -602,12 +603,21 @@ Return: --*/ { UINTN Index; + UINT64 EbdaAddress; // // Prepare Low Memory // 0x18 pages is 72 KB. // - gHob->MemoryFreeUnder1MB.ResourceLength = EFI_MEMORY_BELOW_1MB_END - EFI_MEMORY_BELOW_1MB_START; + EbdaAddress = ((UINT64)(*(UINT16 *)(UINTN)(EBDA_VALUE_ADDRESS))) << 4; + if (EbdaAddress < 0x9A000 || EbdaAddress > EFI_MEMORY_BELOW_1MB_END) { + // + // EBDA should not go below 0x9A000 in any implementation, + // so add check here to make sure EBDA_VALUE_ADDRESS has a valid value. + // + EbdaAddress = EFI_MEMORY_BELOW_1MB_END; + } + gHob->MemoryFreeUnder1MB.ResourceLength = EbdaAddress - EFI_MEMORY_BELOW_1MB_START; gHob->MemoryFreeUnder1MB.PhysicalStart = EFI_MEMORY_BELOW_1MB_START; // -- cgit v1.2.3