[PATCH v1 0/2] MdeModulePkg: Resolve buffer cross boundary access in Ramdisk

[PATCH v1 0/2] MdeModulePkg: Resolve buffer cross boundary access in Ramdisk

[Hao Wu]

The series will resolve a buffer cross boundary access issue during the
use of RAM disks. It is the mitigation for issue CVE-2018-12180.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>

Hao Wu (2):
  MdeModulePkg/PartitionDxe: Ensure blocksize can hold MBR (CVE FIX)
  MdeModulePkg/RamDiskDxe: Ramdisk size be multiple of BlkSize (CVE FIX)

 MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskImpl.h     |  6 +++---
 MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c           |  9 ++++++++-
 MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c           |  9 ++++++++-
 MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskBlockIo.c  | 20 ++++++++++++++------
 MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskProtocol.c |  5 +++--
 5 files changed, 36 insertions(+), 13 deletions(-)

-- 
2.12.0.windows.1

[PATCH v1 1/2] MdeModulePkg/PartitionDxe: Ensure blocksize can hold MBR (CVE FIX)

[Hao Wu]

Fix CVE-2018-12180
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: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@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
@@ -237,6 +237,13 @@ 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
   //
   ProtectiveMbr = AllocatePool (BlockSize);
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;
-- 
2.12.0.windows.1

[PATCH v1 2/2] MdeModulePkg/RamDiskDxe: Ramdisk size be multiple of BlkSize (CVE FIX)

[Hao Wu]

Fix CVE-2018-12180
https://bugzilla.tianocore.org/show_bug.cgi?id=1134

Originally, the block size of created Ram disks is hard-coded to 512
bytes. However, if the total size of the Ram disk is not a multiple of 512
bytes, there will be potential memory access issues when dealing with the
last block of the Ram disk.

This commit will adjust the block size of the Ram disks to ensure that the
total size is a multiple of the block size.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
---
 MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskImpl.h     |  6 +++---
 MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskBlockIo.c  | 20 ++++++++++++++------
 MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskProtocol.c |  5 +++--
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskImpl.h b/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskImpl.h
index 08a8ca94c9..72f2bfe179 100644
--- a/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskImpl.h
+++ b/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskImpl.h
@@ -1,7 +1,7 @@
 /** @file
   The header file of RamDiskDxe driver.
 
-  Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2016 - 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
@@ -49,9 +49,9 @@
 ///
 
 //
-// Block size for RAM disk
+// Default block size for RAM disk
 //
-#define RAM_DISK_BLOCK_SIZE 512
+#define RAM_DISK_DEFAULT_BLOCK_SIZE 512
 
 //
 // Iterate through the double linked list. NOT delete safe
diff --git a/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskBlockIo.c b/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskBlockIo.c
index 4f74b5ef15..8926ad7d2f 100644
--- a/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskBlockIo.c
+++ b/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskBlockIo.c
@@ -1,7 +1,7 @@
 /** @file
   Produce EFI_BLOCK_IO_PROTOCOL on a RAM disk device.
 
-  Copyright (c) 2016 - 2018, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2016 - 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
@@ -54,6 +54,7 @@ RamDiskInitBlockIo (
   EFI_BLOCK_IO_PROTOCOL           *BlockIo;
   EFI_BLOCK_IO2_PROTOCOL          *BlockIo2;
   EFI_BLOCK_IO_MEDIA              *Media;
+  UINT32                          Remainder;
 
   BlockIo  = &PrivateData->BlockIo;
   BlockIo2 = &PrivateData->BlockIo2;
@@ -69,11 +70,18 @@ RamDiskInitBlockIo (
   Media->LogicalPartition = FALSE;
   Media->ReadOnly         = FALSE;
   Media->WriteCaching     = FALSE;
-  Media->BlockSize        = RAM_DISK_BLOCK_SIZE;
-  Media->LastBlock        = DivU64x32 (
-                              PrivateData->Size + RAM_DISK_BLOCK_SIZE - 1,
-                              RAM_DISK_BLOCK_SIZE
-                              ) - 1;
+
+  for (Media->BlockSize = RAM_DISK_DEFAULT_BLOCK_SIZE;
+       Media->BlockSize >= 1;
+       Media->BlockSize = Media->BlockSize >> 1) {
+    Media->LastBlock = DivU64x32Remainder (PrivateData->Size, Media->BlockSize, &Remainder) - 1;
+    if (Remainder == 0) {
+      break;
+    }
+  }
+  ASSERT (Media->BlockSize != 0);
+
+  return;
 }
 
 
diff --git a/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskProtocol.c b/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskProtocol.c
index 6784e2b2f1..e8250d5c1b 100644
--- a/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskProtocol.c
+++ b/MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskProtocol.c
@@ -1,7 +1,7 @@
 /** @file
   The realization of EFI_RAM_DISK_PROTOCOL.
 
-  Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2016 - 2019, Intel Corporation. All rights reserved.<BR>
   (C) Copyright 2016 Hewlett Packard Enterprise Development LP<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
@@ -613,7 +613,8 @@ RamDiskRegister (
   //
   // Add check to prevent data read across the memory boundary
   //
-  if (RamDiskBase + RamDiskSize > ((UINTN) -1) - RAM_DISK_BLOCK_SIZE + 1) {
+  if ((RamDiskSize > MAX_UINTN) ||
+      (RamDiskBase > MAX_UINTN - RamDiskSize + 1)) {
     return EFI_INVALID_PARAMETER;
   }
 
-- 
2.12.0.windows.1