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


Dong, Eric
 

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@...>
Cc: Ruiyu Ni <ruiyu.ni@...>
---
.../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

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