From fccdb88022c1f6d85c773fce506b10c879063f1d Mon Sep 17 00:00:00 2001
From: Hao Wu <hao.a.wu@intel.com>
Date: Fri, 9 Feb 2018 08:43:01 +0800
Subject: [PATCH] MdeModulePkg/PartitionDxe: Ensure blocksize holds MBR
 (CVE-2018-12180)

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1134

The commit adds checks for detecting GPT and MBR partitions.

These checks will ensure that the device block size is big enough to hold
an MBR (512 bytes).

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
---
 MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c | 9 ++++++++-
 MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c | 9 ++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c b/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
index fe87761bde..d679cc208b 100644
--- a/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
+++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
@@ -14,7 +14,7 @@
   partition content and validate the GPT table and GPT entry.
 
 Copyright (c) 2018 Qualcomm Datacenter Technologies, Inc.
-Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2019, 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
@@ -236,6 +236,13 @@ PartitionInstallGptChildHandles (
 
   GptValidStatus = EFI_NOT_FOUND;
 
+  //
+  // Ensure the block size can hold the MBR
+  //
+  if (BlockSize < sizeof (MASTER_BOOT_RECORD)) {
+    return EFI_NOT_FOUND;
+  }
+
   //
   // Allocate a buffer for the Protective MBR
   //
diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c b/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c
index b1a99ee85b..419f8a17a7 100644
--- a/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c
+++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c
@@ -13,7 +13,7 @@
 
 Copyright (c) 2018 Qualcomm Datacenter Technologies, Inc.
 Copyright (c) 2014, Hewlett-Packard Development Company, L.P.<BR>
-Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2019, 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
@@ -150,6 +150,13 @@ PartitionInstallMbrChildHandles (
   MediaId   = BlockIo->Media->MediaId;
   LastBlock = BlockIo->Media->LastBlock;
 
+  //
+  // Ensure the block size can hold the MBR
+  //
+  if (BlockSize < sizeof (MASTER_BOOT_RECORD)) {
+    return EFI_NOT_FOUND;
+  }
+
   Mbr = AllocatePool (BlockSize);
   if (Mbr == NULL) {
     return Found;
-- 
2.39.2