[Patch 0/2] MdePkg DevicePathLib: Check buffer length before use.

[Patch 0/2] MdePkg DevicePathLib: Check buffer length before use.

[Eric Dong]

In IsDevicePathValid API, code should validate the device path
buffer not exceed the input MaxSize before reference the path
info. This patched series add this check.

Eric Dong (2):
  MdePkg UefiDevicePathLib: Validate buffer length before use buffer.
  MdePkg UefiDevicePathLibDevicePathProtocol: Validate before use.

 .../UefiDevicePathLib/DevicePathUtilities.c        | 25 ++++++++++++++++------
 .../UefiDevicePathLib.c                            | 24 +++++++++++++++------
 2 files changed, 35 insertions(+), 14 deletions(-)

-- 
2.6.4.windows.1

[Patch 1/2] MdePkg UefiDevicePathLib: Validate buffer length before use buffer.

[Eric Dong]

In IsDevicePathValid API, code should validate the device path
buffer not exceed the input MaxSize before reference the path
info.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Eric Dong <eric.dong@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
---
 .../UefiDevicePathLib/DevicePathUtilities.c        | 25 ++++++++++++++++------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/MdePkg/Library/UefiDevicePathLib/DevicePathUtilities.c b/MdePkg/Library/UefiDevicePathLib/DevicePathUtilities.c
index 7f21a60..48743c5 100644
--- a/MdePkg/Library/UefiDevicePathLib/DevicePathUtilities.c
+++ b/MdePkg/Library/UefiDevicePathLib/DevicePathUtilities.c
@@ -8,7 +8,7 @@
   environment varibles. Multi-instance device paths should never be placed
   on a Handle.
 
-  Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2006 - 2016, 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        
@@ -61,25 +61,35 @@ IsDevicePathValid (
 
   ASSERT (DevicePath != NULL);
 
-  for (Count = 0, Size = 0; !IsDevicePathEnd (DevicePath); DevicePath = NextDevicePathNode (DevicePath)) {
+  if (MaxSize == 0){
+    MaxSize = MAX_UINTN;
+  }
+
+  Size = 0;
+  Count = 0;
+
+  while (MaxSize >= sizeof (EFI_DEVICE_PATH_PROTOCOL) && \
+        (MaxSize - sizeof (EFI_DEVICE_PATH_PROTOCOL) >= Size) && \
+        !IsDevicePathEnd (DevicePath)) {
     NodeLength = DevicePathNodeLength (DevicePath);
     if (NodeLength < sizeof (EFI_DEVICE_PATH_PROTOCOL)) {
       return FALSE;
     }
 
-    if (MaxSize > 0) {
-      Size += NodeLength;
-      if (Size + END_DEVICE_PATH_LENGTH > MaxSize) {
-        return FALSE;
-      }
+    if (NodeLength > MAX_UINTN - Size) {
+      return FALSE;
     }
 
+    Size += NodeLength;
+
     if (PcdGet32 (PcdMaximumDevicePathNodeCount) > 0) {
       Count++;
       if (Count >= PcdGet32 (PcdMaximumDevicePathNodeCount)) {
         return FALSE;
       }
     }
+
+    DevicePath = NextDevicePathNode (DevicePath);
   }
 
   //
@@ -88,6 +98,7 @@ IsDevicePathValid (
   return (BOOLEAN) (DevicePathNodeLength (DevicePath) == END_DEVICE_PATH_LENGTH);
 }
 
+
 /**
   Returns the Type field of a device path node.
 
-- 
2.6.4.windows.1

[Patch 2/2] MdePkg UefiDevicePathLibDevicePathProtocol: Validate before use.

[Eric Dong]

In IsDevicePathValid API, code should validate the device path
buffer not exceed the input MaxSize before reference the path
info.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Eric Dong <eric.dong@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
---
 .../UefiDevicePathLib.c                            | 24 +++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c b/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c
index 5cc4b35..ae1000e 100644
--- a/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c
+++ b/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c
@@ -2,7 +2,7 @@
   Library instance that implement UEFI Device Path Library class based on protocol
   gEfiDevicePathUtilitiesProtocolGuid.
 
-  Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2006 - 2016, 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
@@ -103,25 +103,35 @@ IsDevicePathValid (
 
   ASSERT (DevicePath != NULL);
 
-  for (Count = 0, Size = 0; !IsDevicePathEnd (DevicePath); DevicePath = NextDevicePathNode (DevicePath)) {
+  if (MaxSize == 0){
+    MaxSize = MAX_UINTN;
+  }
+
+  Size = 0;
+  Count = 0;
+
+  while (MaxSize >= sizeof (EFI_DEVICE_PATH_PROTOCOL) && \
+        (MaxSize - sizeof (EFI_DEVICE_PATH_PROTOCOL) >= Size) && \
+        !IsDevicePathEnd (DevicePath)) {
     NodeLength = DevicePathNodeLength (DevicePath);
     if (NodeLength < sizeof (EFI_DEVICE_PATH_PROTOCOL)) {
       return FALSE;
     }
 
-    if (MaxSize > 0) {
-      Size += NodeLength;
-      if (Size + END_DEVICE_PATH_LENGTH > MaxSize) {
-        return FALSE;
-      }
+    if (NodeLength > MAX_UINTN - Size) {
+      return FALSE;
     }
 
+    Size += NodeLength;
+
     if (PcdGet32 (PcdMaximumDevicePathNodeCount) > 0) {
       Count++;
       if (Count >= PcdGet32 (PcdMaximumDevicePathNodeCount)) {
         return FALSE;
       }
     }
+
+    DevicePath = NextDevicePathNode (DevicePath);
   }
 
   //
-- 
2.6.4.windows.1

Re: [Patch 0/2] MdePkg DevicePathLib: Check buffer length before use.

[Laszlo Ersek]

On 10/12/16 14:39, Eric Dong wrote:
> In IsDevicePathValid API, code should validate the device path
> buffer not exceed the input MaxSize before reference the path
> info. This patched series add this check.
> 
> Eric Dong (2):
>   MdePkg UefiDevicePathLib: Validate buffer length before use buffer.
>   MdePkg UefiDevicePathLibDevicePathProtocol: Validate before use.
> 
>  .../UefiDevicePathLib/DevicePathUtilities.c        | 25 ++++++++++++++++------
>  .../UefiDevicePathLib.c                            | 24 +++++++++++++++------
>  2 files changed, 35 insertions(+), 14 deletions(-)
> 

Just a syntactic remark: you don't need the backslash (\) after the
trailing logical-and (&&) operators.

Thanks
Laszlo

Re: [Patch 0/2] MdePkg DevicePathLib: Check buffer length before use.

[Ni, Ruiyu]

Please remove the ending back-slash in following lines. They are not needed.
+  while (MaxSize >= sizeof (EFI_DEVICE_PATH_PROTOCOL) && \
+        (MaxSize - sizeof (EFI_DEVICE_PATH_PROTOCOL) >= Size) && \
+        !IsDevicePathEnd (DevicePath)) {

With the above changes, Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>

>-----Original Message-----
>From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Eric Dong
>Sent: Wednesday, October 12, 2016 8:39 PM
>To: edk2-devel@lists.01.org; Kinney, Michael D <michael.d.kinney@intel.com>; Gao, Liming <liming.gao@intel.com>
>Subject: [edk2] [Patch 0/2] MdePkg DevicePathLib: Check buffer length before use.
>
>In IsDevicePathValid API, code should validate the device path
>buffer not exceed the input MaxSize before reference the path
>info. This patched series add this check.
>
>Eric Dong (2):
>  MdePkg UefiDevicePathLib: Validate buffer length before use buffer.
>  MdePkg UefiDevicePathLibDevicePathProtocol: Validate before use.
>
> .../UefiDevicePathLib/DevicePathUtilities.c        | 25 ++++++++++++++++------
> .../UefiDevicePathLib.c                            | 24 +++++++++++++++------
> 2 files changed, 35 insertions(+), 14 deletions(-)
>
>--
>2.6.4.windows.1
>
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