Re: [edk2] [PATCH v2 2/5] MdeModulePkg/FaultTolerantWrite:[CVE-2017-5753]Fix bounds check bypass

2018-09-29 Thread Zeng, Star 
Got it, thanks.

Reviewed-by: Star Zeng 

Star
-Original Message-
From: Wu, Hao A 
Sent: Saturday, September 29, 2018 2:21 PM
To: Zeng, Star ; edk2-devel@lists.01.org
Cc: Yao, Jiewen 
Subject: RE: [PATCH v2 2/5] MdeModulePkg/FaultTolerantWrite:[CVE-2017-5753]Fix 
bounds check bypass

> -Original Message-
> From: Zeng, Star
> Sent: Saturday, September 29, 2018 2:11 PM
> To: Wu, Hao A; edk2-devel@lists.01.org
> Cc: Yao, Jiewen; Zeng, Star
> Subject: RE: [PATCH v2 2/5] MdeModulePkg/FaultTolerantWrite:[CVE-2017-
> 5753]Fix bounds check bypass
> 
> Please double check whether the AsmLfence calling should be before the 
> line below.
> 
> PrivateData = (VOID *)>Data[Length];

Hi,

The above code is getting the address of a possible cross bounday access during 
the speculative execution.

I also checked that the subsequent usage of 'PrivateData' does not have a code 
pattern of the 'Bounds check bypass' issue. So I think the
AsmLfence() is not needed here.

Best Regards,
Hao Wu

> 
> 
> Thanks,
> Star
> -Original Message-
> From: Wu, Hao A
> Sent: Tuesday, September 25, 2018 2:13 PM
> To: edk2-devel@lists.01.org
> Cc: Wu, Hao A ; Yao, Jiewen 
> ; Zeng, Star 
> Subject: [PATCH v2 2/5] MdeModulePkg/FaultTolerantWrite:[CVE-2017-
> 5753]Fix bounds check bypass
> 
> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1194
> 
> Speculative execution is used by processor to avoid having to wait for 
> data to arrive from memory, or for previous operations to finish, the 
> processor may speculate as to what will be executed.
> 
> If the speculation is incorrect, the speculatively executed 
> instructions might leave hints such as which memory locations have been 
> brought into cache.
> Malicious actors can use the bounds check bypass method (code gadgets 
> with controlled external inputs) to infer data values that have been 
> used in speculative operations to reveal secrets which should not 
> otherwise be accessed.
> 
> This commit will focus on the SMI handler(s) registered within the 
> FaultTolerantWriteDxe driver and insert AsmLfence API to mitigate the 
> bounds check bypass issue.
> 
> For SMI handler SmmFaultTolerantWriteHandler():
> 
> Under "case FTW_FUNCTION_WRITE:", 'SmmFtwWriteHeader->Length' can be a 
> potential cross boundary access of the 'CommBuffer' (controlled 
> external
> inputs) during speculative execution. This cross boundary access is 
> later passed as parameter 'Length' into function FtwWrite().
> 
> Within function FtwWrite(), the value of 'Length' can be inferred by code:
> "CopyMem (MyBuffer + Offset, Buffer, Length);". One can observe which 
> part of the content within 'Buffer' was brought into cache to possibly 
> reveal the value of 'Length'.
> 
> Hence, this commit adds a AsmLfence() after the boundary/range checks 
> of 'CommBuffer' to prevent the speculative execution.
> 
> A more detailed explanation of the purpose of commit is under the 
> 'Bounds check bypass mitigation' section of the below link:
> https://software.intel.com/security-software-guidance/insights/host-fi
> rmware- speculative-execution-side-channel-mitigation
> 
> And the document at:
> https://software.intel.com/security-software-guidance/api-
> app/sites/default/files/337879-analyzing-potential-bounds-Check-bypass
> -
> vulnerabilities.pdf
> 
> Cc: Jiewen Yao 
> Cc: Star Zeng 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Hao Wu 
> ---
>  MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
> | 7 +++
>  
> MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf
> | 1 +
>  2 files changed, 8 insertions(+)
> 
> diff --git
> a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
> b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
> index 632313f076..27fcab19b6 100644
> ---
> a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
> +++
> b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm
> +++ .c
> @@ -57,6 +57,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, 
> EITHER EXPRESS OR IMPLIED.
>  #include 
>  #include   #include 
> 
> +#include 
>  #include   #include 
> "FaultTolerantWrite.h"
>  #include "FaultTolerantWriteSmmCommon.h"
> @@ -417,6 +418,12 @@ SmmFaultTolerantWriteHandler (
>   
>   );
>if (!EFI_ERROR (Status)) {
> +//
> +// The AsmLfence() call here is to ensure the previous range/content
> +// checks for the CommBuffer have been completed before calling into
> +// FtwWrite().
> +//
> +AsmLfence ();
>  Status = FtwWrite(
> >FtwInstance,
> SmmFtwWriteHeader->Lba, diff --git 
> a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.i
> n
> f
> b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.i
> n
> f
> index 85d109e8d9..606cc2266b 100644
> ---
>

Re: [edk2] [PATCH v2 2/5] MdeModulePkg/FaultTolerantWrite:[CVE-2017-5753]Fix bounds check bypass

2018-09-29 Thread Wu, Hao A 
> -Original Message-
> From: Zeng, Star
> Sent: Saturday, September 29, 2018 2:11 PM
> To: Wu, Hao A; edk2-devel@lists.01.org
> Cc: Yao, Jiewen; Zeng, Star
> Subject: RE: [PATCH v2 2/5] MdeModulePkg/FaultTolerantWrite:[CVE-2017-
> 5753]Fix bounds check bypass
> 
> Please double check whether the AsmLfence calling should be before the line
> below.
> 
> PrivateData = (VOID *)>Data[Length];

Hi,

The above code is getting the address of a possible cross bounday access
during the speculative execution.

I also checked that the subsequent usage of 'PrivateData' does not have a
code pattern of the 'Bounds check bypass' issue. So I think the
AsmLfence() is not needed here.

Best Regards,
Hao Wu

> 
> 
> Thanks,
> Star
> -Original Message-
> From: Wu, Hao A
> Sent: Tuesday, September 25, 2018 2:13 PM
> To: edk2-devel@lists.01.org
> Cc: Wu, Hao A ; Yao, Jiewen ;
> Zeng, Star 
> Subject: [PATCH v2 2/5] MdeModulePkg/FaultTolerantWrite:[CVE-2017-
> 5753]Fix bounds check bypass
> 
> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1194
> 
> Speculative execution is used by processor to avoid having to wait for data to
> arrive from memory, or for previous operations to finish, the processor may
> speculate as to what will be executed.
> 
> If the speculation is incorrect, the speculatively executed instructions might
> leave hints such as which memory locations have been brought into cache.
> Malicious actors can use the bounds check bypass method (code gadgets with
> controlled external inputs) to infer data values that have been used in
> speculative operations to reveal secrets which should not otherwise be
> accessed.
> 
> This commit will focus on the SMI handler(s) registered within the
> FaultTolerantWriteDxe driver and insert AsmLfence API to mitigate the bounds
> check bypass issue.
> 
> For SMI handler SmmFaultTolerantWriteHandler():
> 
> Under "case FTW_FUNCTION_WRITE:", 'SmmFtwWriteHeader->Length' can be
> a potential cross boundary access of the 'CommBuffer' (controlled external
> inputs) during speculative execution. This cross boundary access is later 
> passed
> as parameter 'Length' into function FtwWrite().
> 
> Within function FtwWrite(), the value of 'Length' can be inferred by code:
> "CopyMem (MyBuffer + Offset, Buffer, Length);". One can observe which part
> of the content within 'Buffer' was brought into cache to possibly reveal the
> value of 'Length'.
> 
> Hence, this commit adds a AsmLfence() after the boundary/range checks of
> 'CommBuffer' to prevent the speculative execution.
> 
> A more detailed explanation of the purpose of commit is under the 'Bounds
> check bypass mitigation' section of the below link:
> https://software.intel.com/security-software-guidance/insights/host-firmware-
> speculative-execution-side-channel-mitigation
> 
> And the document at:
> https://software.intel.com/security-software-guidance/api-
> app/sites/default/files/337879-analyzing-potential-bounds-Check-bypass-
> vulnerabilities.pdf
> 
> Cc: Jiewen Yao 
> Cc: Star Zeng 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Hao Wu 
> ---
>  MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
> | 7 +++
>  MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf
> | 1 +
>  2 files changed, 8 insertions(+)
> 
> diff --git
> a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
> b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
> index 632313f076..27fcab19b6 100644
> ---
> a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
> +++
> b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm
> +++ .c
> @@ -57,6 +57,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY
> KIND, EITHER EXPRESS OR IMPLIED.
>  #include 
>  #include   #include 
> +#include 
>  #include   #include
> "FaultTolerantWrite.h"
>  #include "FaultTolerantWriteSmmCommon.h"
> @@ -417,6 +418,12 @@ SmmFaultTolerantWriteHandler (
>   
>   );
>if (!EFI_ERROR (Status)) {
> +//
> +// The AsmLfence() call here is to ensure the previous range/content
> +// checks for the CommBuffer have been completed before calling into
> +// FtwWrite().
> +//
> +AsmLfence ();
>  Status = FtwWrite(
> >FtwInstance,
> SmmFtwWriteHeader->Lba, diff --git
> a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.in
> f
> b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.in
> f
> index 85d109e8d9..606cc2266b 100644
> ---
> a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.in
> f
> +++
> b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm
> +++ .inf
> @@ -55,6 +55,7 @@
>PcdLib
>ReportStatusCodeLib
>SmmMemLib
> +  BaseLib
> 
>  [Guids]
>#
> --
> 2.12.0.windows.1

___
edk2-devel

Re: [edk2] [PATCH v2 2/5] MdeModulePkg/FaultTolerantWrite:[CVE-2017-5753]Fix bounds check bypass

2018-09-29 Thread Zeng, Star 
Please double check whether the AsmLfence calling should be before the line 
below.

PrivateData = (VOID *)>Data[Length];


Thanks,
Star
-Original Message-
From: Wu, Hao A 
Sent: Tuesday, September 25, 2018 2:13 PM
To: edk2-devel@lists.01.org
Cc: Wu, Hao A ; Yao, Jiewen ; Zeng, 
Star 
Subject: [PATCH v2 2/5] MdeModulePkg/FaultTolerantWrite:[CVE-2017-5753]Fix 
bounds check bypass

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1194

Speculative execution is used by processor to avoid having to wait for data to 
arrive from memory, or for previous operations to finish, the processor may 
speculate as to what will be executed.

If the speculation is incorrect, the speculatively executed instructions might 
leave hints such as which memory locations have been brought into cache. 
Malicious actors can use the bounds check bypass method (code gadgets with 
controlled external inputs) to infer data values that have been used in 
speculative operations to reveal secrets which should not otherwise be accessed.

This commit will focus on the SMI handler(s) registered within the 
FaultTolerantWriteDxe driver and insert AsmLfence API to mitigate the bounds 
check bypass issue.

For SMI handler SmmFaultTolerantWriteHandler():

Under "case FTW_FUNCTION_WRITE:", 'SmmFtwWriteHeader->Length' can be a 
potential cross boundary access of the 'CommBuffer' (controlled external
inputs) during speculative execution. This cross boundary access is later 
passed as parameter 'Length' into function FtwWrite().

Within function FtwWrite(), the value of 'Length' can be inferred by code:
"CopyMem (MyBuffer + Offset, Buffer, Length);". One can observe which part of 
the content within 'Buffer' was brought into cache to possibly reveal the value 
of 'Length'.

Hence, this commit adds a AsmLfence() after the boundary/range checks of 
'CommBuffer' to prevent the speculative execution.

A more detailed explanation of the purpose of commit is under the 'Bounds check 
bypass mitigation' section of the below link:
https://software.intel.com/security-software-guidance/insights/host-firmware-speculative-execution-side-channel-mitigation

And the document at:
https://software.intel.com/security-software-guidance/api-app/sites/default/files/337879-analyzing-potential-bounds-Check-bypass-vulnerabilities.pdf

Cc: Jiewen Yao 
Cc: Star Zeng 
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu 
---
 MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c   | 7 
+++
 MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf | 1 +
 2 files changed, 8 insertions(+)

diff --git 
a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c 
b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
index 632313f076..27fcab19b6 100644
--- a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
+++ b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm
+++ .c
@@ -57,6 +57,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER 
EXPRESS OR IMPLIED.
 #include 
 #include   #include 
+#include 
 #include   #include "FaultTolerantWrite.h"
 #include "FaultTolerantWriteSmmCommon.h"
@@ -417,6 +418,12 @@ SmmFaultTolerantWriteHandler (
  
  );
   if (!EFI_ERROR (Status)) {
+//
+// The AsmLfence() call here is to ensure the previous range/content
+// checks for the CommBuffer have been completed before calling into
+// FtwWrite().
+//
+AsmLfence ();
 Status = FtwWrite(
>FtwInstance,
SmmFtwWriteHeader->Lba, diff --git 
a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf 
b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf
index 85d109e8d9..606cc2266b 100644
--- a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf
+++ b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm
+++ .inf
@@ -55,6 +55,7 @@
   PcdLib
   ReportStatusCodeLib
   SmmMemLib
+  BaseLib
 
 [Guids]
   #
--
2.12.0.windows.1

___
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[edk2] [PATCH v2 2/5] MdeModulePkg/FaultTolerantWrite:[CVE-2017-5753]Fix bounds check bypass

2018-09-25 Thread Hao Wu 
REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1194

Speculative execution is used by processor to avoid having to wait for
data to arrive from memory, or for previous operations to finish, the
processor may speculate as to what will be executed.

If the speculation is incorrect, the speculatively executed instructions
might leave hints such as which memory locations have been brought into
cache. Malicious actors can use the bounds check bypass method (code
gadgets with controlled external inputs) to infer data values that have
been used in speculative operations to reveal secrets which should not
otherwise be accessed.

This commit will focus on the SMI handler(s) registered within the
FaultTolerantWriteDxe driver and insert AsmLfence API to mitigate the
bounds check bypass issue.

For SMI handler SmmFaultTolerantWriteHandler():

Under "case FTW_FUNCTION_WRITE:", 'SmmFtwWriteHeader->Length' can be a
potential cross boundary access of the 'CommBuffer' (controlled external
inputs) during speculative execution. This cross boundary access is later
passed as parameter 'Length' into function FtwWrite().

Within function FtwWrite(), the value of 'Length' can be inferred by code:
"CopyMem (MyBuffer + Offset, Buffer, Length);". One can observe which part
of the content within 'Buffer' was brought into cache to possibly reveal
the value of 'Length'.

Hence, this commit adds a AsmLfence() after the boundary/range checks of
'CommBuffer' to prevent the speculative execution.

A more detailed explanation of the purpose of commit is under the
'Bounds check bypass mitigation' section of the below link:
https://software.intel.com/security-software-guidance/insights/host-firmware-speculative-execution-side-channel-mitigation

And the document at:
https://software.intel.com/security-software-guidance/api-app/sites/default/files/337879-analyzing-potential-bounds-Check-bypass-vulnerabilities.pdf

Cc: Jiewen Yao 
Cc: Star Zeng 
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu 
---
 MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c   | 7 
+++
 MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf | 1 +
 2 files changed, 8 insertions(+)

diff --git 
a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c 
b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
index 632313f076..27fcab19b6 100644
--- a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
+++ b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.c
@@ -57,6 +57,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER 
EXPRESS OR IMPLIED.
 #include 
 #include 
 #include 
+#include 
 #include 
 #include "FaultTolerantWrite.h"
 #include "FaultTolerantWriteSmmCommon.h"
@@ -417,6 +418,12 @@ SmmFaultTolerantWriteHandler (
  
  );
   if (!EFI_ERROR (Status)) {
+//
+// The AsmLfence() call here is to ensure the previous range/content
+// checks for the CommBuffer have been completed before calling into
+// FtwWrite().
+//
+AsmLfence ();
 Status = FtwWrite(
>FtwInstance,
SmmFtwWriteHeader->Lba,
diff --git 
a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf 
b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf
index 85d109e8d9..606cc2266b 100644
--- a/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf
+++ b/MdeModulePkg/Universal/FaultTolerantWriteDxe/FaultTolerantWriteSmm.inf
@@ -55,6 +55,7 @@
   PcdLib
   ReportStatusCodeLib
   SmmMemLib
+  BaseLib
 
 [Guids]
   #
-- 
2.12.0.windows.1

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