From 8a7cd4ba31848171f596a1eb1df0bc06633d3276 Mon Sep 17 00:00:00 2001
From: Laszlo Ersek <lersek@redhat.com>
Date: Fri, 22 Mar 2019 21:53:21 +0100
Subject: [PATCH 5/8] MdeModulePkg/UdfDxe: Add boundary check the read of
 FE/EFE
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Message-id: <20190322205323.17693-4-lersek@redhat.com>
Patchwork-id: 85130
O-Subject:  [RHEL-7.7 ovmf PATCH 3/5] MdeModulePkg/UdfDxe: Add boundary check the
	read of FE/EFE
Bugzilla: 1691647
Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Vitaly Kuznetsov <vkuznets@redhat.com>

From: Hao Wu <hao.a.wu@intel.com>

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=828

Within ReadFile():

Add checks to ensure that when getting the raw data or the Allocation
Descriptors' data from a FE/EFE, it will not consume data beyond the
size of a FE/EFE.

Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Paulo Alcantara <palcantara@suse.de>
Acked-by: Star Zeng <star.zeng@intel.com>
(cherry picked from commit 5c0748f43f4e1cc15fdd0be64a764eacd7df92f6)
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 .../Universal/Disk/UdfDxe/FileSystemOperations.c   | 54 ++++++++++++++++++++--
 1 file changed, 50 insertions(+), 4 deletions(-)

diff --git a/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c b/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
index 424f41c..0012075 100644
--- a/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
+++ b/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
@@ -504,15 +504,27 @@ DuplicateFe (
 
   NOTE: The FE/EFE can be thought it was an inode.
 
+  @attention This is boundary function that may receive untrusted input.
+  @attention The input is from FileSystem.
+
+  The (Extended) File Entry is external input, so this routine will do basic
+  validation for (Extended) File Entry and report status.
+
   @param[in]  FileEntryData       (Extended) File Entry pointer.
+  @param[in]  FileEntrySize       Size of the (Extended) File Entry specified
+                                  by FileEntryData.
   @param[out] Data                Buffer contains the raw data of a given
                                   (Extended) File Entry.
   @param[out] Length              Length of the data in Buffer.
 
+  @retval EFI_SUCCESS             Raw data and size of the FE/EFE was read.
+  @retval EFI_VOLUME_CORRUPTED    The file system structures are corrupted.
+
 **/
-VOID
+EFI_STATUS
 GetFileEntryData (
   IN   VOID    *FileEntryData,
+  IN   UINTN   FileEntrySize,
   OUT  VOID    **Data,
   OUT  UINT64  *Length
   )
@@ -536,20 +548,40 @@ GetFileEntryData (
     *Data    = (VOID *)((UINT8 *)FileEntry->Data +
                         FileEntry->LengthOfExtendedAttributes);
   }
+
+  if ((*Length > FileEntrySize) ||
+      ((UINTN)FileEntryData > (UINTN)(*Data)) ||
+      ((UINTN)(*Data) - (UINTN)FileEntryData > FileEntrySize - *Length)) {
+    return EFI_VOLUME_CORRUPTED;
+  }
+  return EFI_SUCCESS;
 }
 
 /**
   Get Allocation Descriptors' data information from a given FE/EFE.
 
+  @attention This is boundary function that may receive untrusted input.
+  @attention The input is from FileSystem.
+
+  The (Extended) File Entry is external input, so this routine will do basic
+  validation for (Extended) File Entry and report status.
+
   @param[in]  FileEntryData       (Extended) File Entry pointer.
+  @param[in]  FileEntrySize       Size of the (Extended) File Entry specified
+                                  by FileEntryData.
   @param[out] AdsData             Buffer contains the Allocation Descriptors'
                                   data from a given FE/EFE.
   @param[out] Length              Length of the data in AdsData.
 
+  @retval EFI_SUCCESS             The data and size of Allocation Descriptors
+                                  were read from the FE/EFE.
+  @retval EFI_VOLUME_CORRUPTED    The file system structures are corrupted.
+
 **/
-VOID
+EFI_STATUS
 GetAdsInformation (
   IN   VOID    *FileEntryData,
+  IN   UINTN   FileEntrySize,
   OUT  VOID    **AdsData,
   OUT  UINT64  *Length
   )
@@ -573,6 +605,13 @@ GetAdsInformation (
     *AdsData = (VOID *)((UINT8 *)FileEntry->Data +
                         FileEntry->LengthOfExtendedAttributes);
   }
+
+  if ((*Length > FileEntrySize) ||
+      ((UINTN)FileEntryData > (UINTN)(*AdsData)) ||
+      ((UINTN)(*AdsData) - (UINTN)FileEntryData > FileEntrySize - *Length)) {
+    return EFI_VOLUME_CORRUPTED;
+  }
+  return EFI_SUCCESS;
 }
 
 /**
@@ -1066,7 +1105,10 @@ ReadFile (
     //
     // There are no extents for this FE/EFE. All data is inline.
     //
-    GetFileEntryData (FileEntryData, &Data, &Length);
+    Status = GetFileEntryData (FileEntryData, Volume->FileEntrySize, &Data, &Length);
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
 
     if (ReadFileInfo->Flags == ReadFileGetFileSize) {
       ReadFileInfo->ReadLength = Length;
@@ -1110,7 +1152,11 @@ ReadFile (
     // This FE/EFE contains a run of Allocation Descriptors. Get data + size
     // for start reading them out.
     //
-    GetAdsInformation (FileEntryData, &Data, &Length);
+    Status = GetAdsInformation (FileEntryData, Volume->FileEntrySize, &Data, &Length);
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
+
     AdOffset = 0;
 
     for (;;) {
-- 
1.8.3.1