Re: [Patch] SecurityPkg Tpm2CommandLib: Fix TPM2.0 response memory overflow

["Long, Qin" <qin.long@intel.com>]

Hi, Chao,

One minor suggestion to add the comment to explain the following value "8": the number of digests in list is not greater than 8 per TPML_DIGEST definition. 
+  if (PcrValues->count > 8) {
+    return EFI_DEVICE_ERROR;
+  }

Other looks good to me. 

Reviewed-by: Long Qin <qin.long@intel.com>


Best Regards & Thanks,
LONG, Qin

-----Original Message-----
From: Zhang, Chao B 
Sent: Tuesday, March 20, 2018 4:36 PM
To: edk2-devel@lists.01.org
Cc: Long, Qin <qin.long@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>; Zhang, Chao B <chao.b.zhang@intel.com>
Subject: [Patch] SecurityPkg Tpm2CommandLib: Fix TPM2.0 response memory overflow

TPM2.0 command lib always assumes TPM device and transmission channel can respond correctly. But it is not true when communication channel is exploited and wrong data is spoofed. Add more logic to prohibit memory overflow attack.

Cc: Long Qin <qin.long@intel.com>
Cc: Yao Jiewen <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Chao Zhang <chao.b.zhang@intel.com>
Signed-off-by: Zhang, Chao B <chao.b.zhang@intel.com>
---
 .../Library/Tpm2CommandLib/Tpm2Capability.c        | 21 ++++++++++++++-
 .../Tpm2CommandLib/Tpm2EnhancedAuthorization.c     | 16 ++++++++++-
 SecurityPkg/Library/Tpm2CommandLib/Tpm2Integrity.c | 19 ++++++++++---  SecurityPkg/Library/Tpm2CommandLib/Tpm2NVStorage.c | 14 ++++++++--
 SecurityPkg/Library/Tpm2CommandLib/Tpm2Object.c    | 31 +++++++++++++++++++++-
 SecurityPkg/Library/Tpm2CommandLib/Tpm2Sequences.c | 10 ++++++-
 SecurityPkg/Library/Tpm2CommandLib/Tpm2Session.c   |  6 ++++-
 7 files changed, 107 insertions(+), 10 deletions(-)

diff --git a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Capability.c b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Capability.c
index 79e80fb7a9..42afe107a6 100644
--- a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Capability.c
+++ b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Capability.c
@@ -1,9 +1,9 @@
 /** @file
   Implement TPM2 Capability related command.
 
-Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved. <BR>
+Copyright (c) 2013 - 2018, 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  http://opensource.org/licenses/bsd-license.php
 
@@ -110,10 +110,18 @@ Tpm2GetCapability (
 
   if (RecvBufferSize <= sizeof (TPM2_RESPONSE_HEADER) + sizeof (UINT8)) {
     return EFI_DEVICE_ERROR;
   }
 
+  //
+  // Fail if command failed
+  //
+  if (SwapBytes32(RecvBuffer.Header.responseCode) != TPM_RC_SUCCESS) {
+    DEBUG ((EFI_D_ERROR, "Tpm2GetCapability: Response Code error! 0x%08x\r\n", SwapBytes32(RecvBuffer.Header.responseCode)));
+    return EFI_DEVICE_ERROR;
+  }
+
   //
   // Return the response
   //
   *MoreData = RecvBuffer.MoreData;
   //
@@ -327,10 +335,14 @@ Tpm2GetCapabilitySupportedAlg (
   }
   
   CopyMem (AlgList, &TpmCap.data.algorithms, sizeof (TPML_ALG_PROPERTY));
 
   AlgList->count = SwapBytes32 (AlgList->count);
+  if (AlgList->count > MAX_CAP_ALGS) {
+    return EFI_DEVICE_ERROR;
+  }
+
   for (Index = 0; Index < AlgList->count; Index++) {
     AlgList->algProperties[Index].alg = SwapBytes16 (AlgList->algProperties[Index].alg);
     WriteUnaligned32 ((UINT32 *)&AlgList->algProperties[Index].algProperties, SwapBytes32 (ReadUnaligned32 ((UINT32 *)&AlgList->algProperties[Index].algProperties)));
   }
 
@@ -474,13 +486,20 @@ Tpm2GetCapabilityPcrs (
   if (EFI_ERROR (Status)) {
     return Status;
   }
 
   Pcrs->count = SwapBytes32 (TpmCap.data.assignedPCR.count);
+  if (Pcrs->count > HASH_COUNT) {
+    return EFI_DEVICE_ERROR;
+  }
+
   for (Index = 0; Index < Pcrs->count; Index++) {
     Pcrs->pcrSelections[Index].hash = SwapBytes16 (TpmCap.data.assignedPCR.pcrSelections[Index].hash);
     Pcrs->pcrSelections[Index].sizeofSelect = TpmCap.data.assignedPCR.pcrSelections[Index].sizeofSelect;
+    if (Pcrs->pcrSelections[Index].sizeofSelect > PCR_SELECT_MAX) {
+      return EFI_DEVICE_ERROR;
+    }
     CopyMem (Pcrs->pcrSelections[Index].pcrSelect, TpmCap.data.assignedPCR.pcrSelections[Index].pcrSelect, Pcrs->pcrSelections[Index].sizeofSelect);
   }
 
   return EFI_SUCCESS;
 }
diff --git a/SecurityPkg/Library/Tpm2CommandLib/Tpm2EnhancedAuthorization.c b/SecurityPkg/Library/Tpm2CommandLib/Tpm2EnhancedAuthorization.c
index 6f6b3693f8..3e42875b83 100644
--- a/SecurityPkg/Library/Tpm2CommandLib/Tpm2EnhancedAuthorization.c
+++ b/SecurityPkg/Library/Tpm2CommandLib/Tpm2EnhancedAuthorization.c
@@ -1,9 +1,9 @@
 /** @file
   Implement TPM2 EnhancedAuthorization related command.
 
-Copyright (c) 2014 - 2016, Intel Corporation. All rights reserved. <BR>
+Copyright (c) 2014 - 2018, 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  http://opensource.org/licenses/bsd-license.php
 
@@ -178,19 +178,29 @@ Tpm2PolicySecret (
   //
   // Return the response
   //
   Buffer = (UINT8 *)&RecvBuffer.Timeout;
   Timeout->size = SwapBytes16(ReadUnaligned16 ((UINT16 *)Buffer));
+  if (Timeout->size > sizeof(UINT64)) {
+    Status = EFI_DEVICE_ERROR;
+    goto Done;
+  }
+
   Buffer += sizeof(UINT16);
   CopyMem (Timeout->buffer, Buffer, Timeout->size);
 
   PolicyTicket->tag = SwapBytes16(ReadUnaligned16 ((UINT16 *)Buffer));
   Buffer += sizeof(UINT16);
   PolicyTicket->hierarchy = SwapBytes32(ReadUnaligned32 ((UINT32 *)Buffer));
   Buffer += sizeof(UINT32);
   PolicyTicket->digest.size = SwapBytes16(ReadUnaligned16 ((UINT16 *)Buffer));
   Buffer += sizeof(UINT16);
+  if (PolicyTicket->digest.size > sizeof(TPMU_HA)) {
+    Status = EFI_DEVICE_ERROR;
+    goto Done;
+  }
+
   CopyMem (PolicyTicket->digest.buffer, Buffer, PolicyTicket->digest.size);
 
 Done:
   //
   // Clear AuthSession Content
@@ -377,9 +387,13 @@ Tpm2PolicyGetDigest (
 
   //
   // Return the response
   //
   PolicyHash->size = SwapBytes16 (RecvBuffer.PolicyHash.size);
+  if (PolicyHash->size > sizeof(TPMU_HA)) {
+    return EFI_DEVICE_ERROR;
+  }
+
   CopyMem (PolicyHash->buffer, &RecvBuffer.PolicyHash.buffer, PolicyHash->size);
 
   return EFI_SUCCESS;
 }
diff --git a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Integrity.c b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Integrity.c
index 8eacfe6c13..9c0b70dd93 100644
--- a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Integrity.c
+++ b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Integrity.c
@@ -1,9 +1,9 @@
 /** @file
   Implement TPM2 Integrity related command.
 
-Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved. <BR>
+Copyright (c) 2013 - 2018, 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  http://opensource.org/licenses/bsd-license.php
 
@@ -277,10 +277,14 @@ Tpm2PcrEvent (
   // Unmarshal the response
   //
   Buffer = (UINT8 *)&Res.Digests;
 
   Digests->count = SwapBytes32 (ReadUnaligned32 ((UINT32 *)Buffer));
+  if (Digests->count > HASH_COUNT) {
+    return EFI_DEVICE_ERROR;
+  }
+
   Buffer += sizeof(UINT32);
   for (Index = 0; Index < Digests->count; Index++) {
     Digests->digests[Index].hashAlg = SwapBytes16 (ReadUnaligned16 ((UINT16 *)Buffer));
     Buffer += sizeof(UINT16);
     DigestSize = GetHashSizeFromAlgo (Digests->digests[Index].hashAlg);
@@ -381,28 +385,37 @@ Tpm2PcrRead (
   if (RecvBufferSize < sizeof (TPM2_RESPONSE_HEADER) + sizeof(RecvBuffer.PcrUpdateCounter) + sizeof(RecvBuffer.PcrSelectionOut.count)) {
     DEBUG ((EFI_D_ERROR, "Tpm2PcrRead - RecvBufferSize Error - %x\n", RecvBufferSize));
     return EFI_DEVICE_ERROR;
   }
   PcrSelectionOut->count = SwapBytes32(RecvBuffer.PcrSelectionOut.count);
-  if (RecvBufferSize < sizeof (TPM2_RESPONSE_HEADER) + sizeof(RecvBuffer.PcrUpdateCounter) + sizeof(RecvBuffer.PcrSelectionOut.count) + sizeof(RecvBuffer.PcrSelectionOut.pcrSelections[0]) * PcrSelectionOut->count) {
-    DEBUG ((EFI_D_ERROR, "Tpm2PcrRead - RecvBufferSize Error - %x\n", RecvBufferSize));
+  if (PcrSelectionOut->count > HASH_COUNT || RecvBufferSize < sizeof (TPM2_RESPONSE_HEADER) + sizeof(RecvBuffer.PcrUpdateCounter) + sizeof(RecvBuffer.PcrSelectionOut.count) + sizeof(RecvBuffer.PcrSelectionOut.pcrSelections[0]) * PcrSelectionOut->count) {
+    DEBUG ((EFI_D_ERROR, "Tpm2PcrRead - Digests->count -%x or 
+ RecvBufferSize Error - %x\n", PcrSelectionOut->count, 
+ RecvBufferSize));
     return EFI_DEVICE_ERROR;
   }
   for (Index = 0; Index < PcrSelectionOut->count; Index++) {
     PcrSelectionOut->pcrSelections[Index].hash = SwapBytes16(RecvBuffer.PcrSelectionOut.pcrSelections[Index].hash);
     PcrSelectionOut->pcrSelections[Index].sizeofSelect = RecvBuffer.PcrSelectionOut.pcrSelections[Index].sizeofSelect;
+    if (PcrSelectionOut->pcrSelections[Index].sizeofSelect > PCR_SELECT_MAX) {
+      return EFI_DEVICE_ERROR;
+    }
     CopyMem (&PcrSelectionOut->pcrSelections[Index].pcrSelect, &RecvBuffer.PcrSelectionOut.pcrSelections[Index].pcrSelect, PcrSelectionOut->pcrSelections[Index].sizeofSelect);
   }
 
   //
   // PcrValues
   //
   PcrValuesOut = (TPML_DIGEST *)((UINT8 *)&RecvBuffer + sizeof (TPM2_RESPONSE_HEADER) + sizeof(RecvBuffer.PcrUpdateCounter) + sizeof(RecvBuffer.PcrSelectionOut.count) + sizeof(RecvBuffer.PcrSelectionOut.pcrSelections[0]) * PcrSelectionOut->count);
   PcrValues->count = SwapBytes32(PcrValuesOut->count);
+  if (PcrValues->count > 8) {
+    return EFI_DEVICE_ERROR;
+  }
   Digests = PcrValuesOut->digests;
   for (Index = 0; Index < PcrValues->count; Index++) {
     PcrValues->digests[Index].size = SwapBytes16(Digests->size);
+    if (PcrValues->digests[Index].size > sizeof(TPMU_HA)) {
+      return EFI_DEVICE_ERROR;
+    }
     CopyMem (&PcrValues->digests[Index].buffer, &Digests->buffer, PcrValues->digests[Index].size);
     Digests = (TPM2B_DIGEST *)((UINT8 *)Digests + sizeof(Digests->size) + PcrValues->digests[Index].size);
   }
 
   return EFI_SUCCESS;
diff --git a/SecurityPkg/Library/Tpm2CommandLib/Tpm2NVStorage.c b/SecurityPkg/Library/Tpm2CommandLib/Tpm2NVStorage.c
index 9508022132..2b87260764 100644
--- a/SecurityPkg/Library/Tpm2CommandLib/Tpm2NVStorage.c
+++ b/SecurityPkg/Library/Tpm2CommandLib/Tpm2NVStorage.c
@@ -1,9 +1,9 @@
 /** @file
   Implement TPM2 NVStorage related command.
 
-Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved. <BR>
+Copyright (c) 2013 - 2018, 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  http://opensource.org/licenses/bsd-license.php
 
@@ -232,13 +232,18 @@ Tpm2NvReadPublic (
 
   //
   // Basic check
   //
   NvPublicSize = SwapBytes16 (RecvBuffer.NvPublic.size);
+  if (NvPublicSize > sizeof(TPMS_NV_PUBLIC)) {
+    return EFI_DEVICE_ERROR;
+  }
+
   NvNameSize = SwapBytes16 (ReadUnaligned16 ((UINT16 *)((UINT8 *)&RecvBuffer + sizeof(TPM2_RESPONSE_HEADER) + sizeof(UINT16) + NvPublicSize)));
 
-  if (RecvBufferSize != sizeof(TPM2_RESPONSE_HEADER) + sizeof(UINT16) + NvPublicSize + sizeof(UINT16) + NvNameSize) {
+  if (NvNameSize > sizeof(TPMU_NAME) ||
+      (RecvBufferSize != sizeof(TPM2_RESPONSE_HEADER) + sizeof(UINT16) 
+ + NvPublicSize + sizeof(UINT16) + NvNameSize)) {
     DEBUG ((EFI_D_ERROR, "Tpm2NvReadPublic - RecvBufferSize Error - NvPublicSize %x, NvNameSize %x\n", RecvBufferSize, NvNameSize));
     return EFI_NOT_FOUND;
   }
 
   //
@@ -630,10 +635,15 @@ Tpm2NvRead (
 
   //
   // Return the response
   //
   OutData->size = SwapBytes16 (RecvBuffer.Data.size);
+  if (OutData->size > MAX_DIGEST_BUFFER) {
+    Status = EFI_DEVICE_ERROR;
+    goto Done;
+  }
+
   CopyMem (OutData->buffer, &RecvBuffer.Data.buffer, OutData->size);
   
 Done:
   //
   // Clear AuthSession Content
diff --git a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Object.c b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Object.c
index e070ff2f74..e9f693b65d 100644
--- a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Object.c
+++ b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Object.c
@@ -1,9 +1,9 @@
 /** @file
   Implement TPM2 Object related command.
 
-Copyright (c) 2017, Intel Corporation. All rights reserved. <BR>
+Copyright (c) 2017 - 2018, 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  http://opensource.org/licenses/bsd-license.php
 
@@ -107,15 +107,26 @@ Tpm2ReadPublic (
 
   //
   // Basic check
   //
   OutPublicSize = SwapBytes16 (RecvBuffer.OutPublic.size);
+  if (OutPublicSize > sizeof(TPMT_PUBLIC)) {
+    return EFI_DEVICE_ERROR;
+  }
+
   NameSize = SwapBytes16 (ReadUnaligned16 ((UINT16 *)((UINT8 *)&RecvBuffer + sizeof(TPM2_RESPONSE_HEADER) +
                           sizeof(UINT16) + OutPublicSize)));
+  if (NameSize > sizeof(TPMU_NAME)) {
+    return EFI_DEVICE_ERROR;
+  }
+
   QualifiedNameSize = SwapBytes16 (ReadUnaligned16 ((UINT16 *)((UINT8 *)&RecvBuffer + sizeof(TPM2_RESPONSE_HEADER) +
                                    sizeof(UINT16) + OutPublicSize +
                                    sizeof(UINT16) + NameSize)));
+  if (QualifiedNameSize > sizeof(TPMU_NAME)) {
+    return EFI_DEVICE_ERROR;
+  }
 
   if (RecvBufferSize != sizeof(TPM2_RESPONSE_HEADER) + sizeof(UINT16) + OutPublicSize + sizeof(UINT16) + NameSize + sizeof(UINT16) + QualifiedNameSize) {
     DEBUG ((DEBUG_ERROR, "Tpm2ReadPublic - RecvBufferSize %x Error - OutPublicSize %x, NameSize %x, QualifiedNameSize %x\n", RecvBufferSize, OutPublicSize, NameSize, QualifiedNameSize));
     return EFI_DEVICE_ERROR;
   }
@@ -130,10 +141,13 @@ Tpm2ReadPublic (
   OutPublic->publicArea.nameAlg = SwapBytes16 (OutPublic->publicArea.nameAlg);
   WriteUnaligned32 ((UINT32 *)&OutPublic->publicArea.objectAttributes, SwapBytes32 (ReadUnaligned32 ((UINT32 *)&OutPublic->publicArea.objectAttributes)));
   Buffer = (UINT8 *)&RecvBuffer.OutPublic.publicArea.authPolicy;
   OutPublic->publicArea.authPolicy.size = SwapBytes16 (ReadUnaligned16 ((UINT16 *)Buffer));
   Buffer += sizeof(UINT16);
+  if (OutPublic->publicArea.authPolicy.size > sizeof(TPMU_HA)) {
+    return EFI_DEVICE_ERROR;
+  }
   CopyMem (OutPublic->publicArea.authPolicy.buffer, Buffer, OutPublic->publicArea.authPolicy.size);
   Buffer += OutPublic->publicArea.authPolicy.size;
 
   // TPMU_PUBLIC_PARMS
   switch (OutPublic->publicArea.type) { @@ -305,32 +319,47 @@ Tpm2ReadPublic (
   // TPMU_PUBLIC_ID
   switch (OutPublic->publicArea.type) {
   case TPM_ALG_KEYEDHASH:
     OutPublic->publicArea.unique.keyedHash.size = SwapBytes16 (ReadUnaligned16 ((UINT16 *)Buffer));
     Buffer += sizeof(UINT16);
+    if(OutPublic->publicArea.unique.keyedHash.size > sizeof(TPMU_HA)) {
+      return EFI_DEVICE_ERROR;
+    }
     CopyMem (OutPublic->publicArea.unique.keyedHash.buffer, Buffer, OutPublic->publicArea.unique.keyedHash.size);
     Buffer += OutPublic->publicArea.unique.keyedHash.size;
     break;
   case TPM_ALG_SYMCIPHER:
     OutPublic->publicArea.unique.sym.size = SwapBytes16 (ReadUnaligned16 ((UINT16 *)Buffer));
     Buffer += sizeof(UINT16);
+    if(OutPublic->publicArea.unique.sym.size > sizeof(TPMU_HA)) {
+      return EFI_DEVICE_ERROR;
+    }
     CopyMem (OutPublic->publicArea.unique.sym.buffer, Buffer, OutPublic->publicArea.unique.sym.size);
     Buffer += OutPublic->publicArea.unique.sym.size;
     break;
   case TPM_ALG_RSA:
     OutPublic->publicArea.unique.rsa.size = SwapBytes16 (ReadUnaligned16 ((UINT16 *)Buffer));
     Buffer += sizeof(UINT16);
+    if(OutPublic->publicArea.unique.rsa.size > MAX_RSA_KEY_BYTES) {
+      return EFI_DEVICE_ERROR;
+    }
     CopyMem (OutPublic->publicArea.unique.rsa.buffer, Buffer, OutPublic->publicArea.unique.rsa.size);
     Buffer += OutPublic->publicArea.unique.rsa.size;
     break;
   case TPM_ALG_ECC:
     OutPublic->publicArea.unique.ecc.x.size = SwapBytes16 (ReadUnaligned16 ((UINT16 *)Buffer));
     Buffer += sizeof(UINT16);
+    if (OutPublic->publicArea.unique.ecc.x.size > MAX_ECC_KEY_BYTES) {
+      return EFI_DEVICE_ERROR;
+    }
     CopyMem (OutPublic->publicArea.unique.ecc.x.buffer, Buffer, OutPublic->publicArea.unique.ecc.x.size);
     Buffer += OutPublic->publicArea.unique.ecc.x.size;
     OutPublic->publicArea.unique.ecc.y.size = SwapBytes16 (ReadUnaligned16 ((UINT16 *)Buffer));
     Buffer += sizeof(UINT16);
+    if (OutPublic->publicArea.unique.ecc.y.size > MAX_ECC_KEY_BYTES) {
+      return EFI_DEVICE_ERROR;
+    }
     CopyMem (OutPublic->publicArea.unique.ecc.y.buffer, Buffer, OutPublic->publicArea.unique.ecc.y.size);
     Buffer += OutPublic->publicArea.unique.ecc.y.size;
     break;
   default:
     return EFI_UNSUPPORTED;
diff --git a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Sequences.c b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Sequences.c
index 305b6f2078..68a445bafc 100644
--- a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Sequences.c
+++ b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Sequences.c
@@ -1,9 +1,9 @@
 /** @file
   Implement TPM2 Sequences related command.
 
-Copyright (c) 2013, Intel Corporation. All rights reserved. <BR>
+Copyright (c) 2013 - 2018, 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  http://opensource.org/licenses/bsd-license.php
 
@@ -373,10 +373,14 @@ Tpm2EventSequenceComplete (
 
   BufferPtr = (UINT8 *)&Res.Results;
 
   // count
   Results->count = SwapBytes32(ReadUnaligned32 ((UINT32 *)BufferPtr));
+  if (Results->count > HASH_COUNT) {
+    return EFI_DEVICE_ERROR;
+  }
+
   BufferPtr += sizeof(UINT32);
 
   for (Index = 0; Index < Results->count; Index++) {
     Results->digests[Index].hashAlg = SwapBytes16(ReadUnaligned16 ((UINT16 *)BufferPtr));
     BufferPtr += sizeof(UINT16);
@@ -494,10 +498,14 @@ Tpm2SequenceComplete (
 
   BufferPtr = (UINT8 *)&Res.Digest;
 
   // digestSize
   Result->size = SwapBytes16(ReadUnaligned16 ((UINT16 *)BufferPtr));
+  if (Result->size > sizeof(TPMU_HA)){
+    return EFI_DEVICE_ERROR;
+  }
+
   BufferPtr += sizeof(UINT16);
 
   CopyMem(
     Result->buffer,
     BufferPtr,
diff --git a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Session.c b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Session.c
index f03b6689ac..0c9b310e54 100644
--- a/SecurityPkg/Library/Tpm2CommandLib/Tpm2Session.c
+++ b/SecurityPkg/Library/Tpm2CommandLib/Tpm2Session.c
@@ -1,9 +1,9 @@
 /** @file
   Implement TPM2 Session related command.
 
-Copyright (c) 2014, Intel Corporation. All rights reserved. <BR>
+Copyright (c) 2014 - 2018, 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  http://opensource.org/licenses/bsd-license.php
 
@@ -161,9 +161,13 @@ Tpm2StartAuthSession (
   //
   // Return the response
   //
   *SessionHandle = SwapBytes32 (RecvBuffer.SessionHandle);
   NonceTPM->size = SwapBytes16 (RecvBuffer.NonceTPM.size);
+  if (NonceTPM->size > sizeof(TPMU_HA)) {
+    return EFI_DEVICE_ERROR;
+  }
+
   CopyMem (NonceTPM->buffer, &RecvBuffer.NonceTPM.buffer, NonceTPM->size);
 
   return EFI_SUCCESS;
 }
--
2.16.2.windows.1