[PATCH v2 0/2][UDK branches][CVE-2017-5753] Additional Bounds Check Bypass issue in SMI handlers

[PATCH v2 0/2][UDK branches][CVE-2017-5753] Additional Bounds Check Bypass issue in SMI handlers

[Hao Wu]

V2 changes:

Add the missing information in the commit message for patch 1/2.


V1 history:

The series aims to mitigate the Bounds Check Bypass (CVE-2017-5753) issues
within SMI handlers. Moreover, this series focuses on those SMI handlers
that exist on the UDK branches but not on the master branch.

Patch 1/2 will be applied on the below UDK branches:
UDK2017
UDK2015
UDK2014.SP1

Patch 2/2 will be applied on the below UDK branches:
UDK2017
UDK2015

A more detailed explanation of the purpose of the series 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: Star Zeng <star.zeng@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>

Hao Wu (2):
  MdeModulePkg/SmmCorePerfLib: [CVE-2017-5753] Fix bounds check bypass
  SecurityPkg/OpalPWSupportLib: [CVE-2017-5753] Fix bounds check bypass

 MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c  | 16 +++++++++++++++-
 SecurityPkg/Library/OpalPasswordSupportLib/OpalPasswordSupportLib.c |  7 ++++++-
 2 files changed, 21 insertions(+), 2 deletions(-)

-- 
2.12.0.windows.1

[PATCH v2 1/2] MdeModulePkg/SmmCorePerfLib: [CVE-2017-5753] Fix bounds check bypass

[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
SmmCorePerformanceLib and insert AsmLfence API to mitigate the bounds
check bypass issue.

For SMI handler SmmPerformanceHandlerEx():

Under "case SMM_PERF_FUNCTION_GET_GAUGE_DATA :",
'SmmPerfCommData->LogEntryKey' can be a potential cross boundary access of
the 'CommBuffer' (controlled external inputs) during speculative
execution. This cross boundary access is then assign to parameter
'LogEntryKey'. And the value of 'LogEntryKey' can be inferred by code:

  CopyMem (
    (UINT8 *) &GaugeDataEx[Index],
    (UINT8 *) &GaugeEntryExArray[LogEntryKey++],
    sizeof (GAUGE_DATA_ENTRY_EX)
    );

One can observe which part of the content within 'GaugeEntryExArray' was
brought into cache to possibly reveal the value of 'LogEntryKey'.

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

And there is 1 similar case for SMI handler SmmPerformanceHandler() as
well. This commit also handles it.

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: Star Zeng <star.zeng@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
---
 MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c b/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c
index cd1f1a5d5f..63c1eea3a2 100644
--- a/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c
+++ b/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c
@@ -16,7 +16,7 @@
 
  SmmPerformanceHandlerEx(), SmmPerformanceHandler() will receive untrusted input and do basic validation.
 
-Copyright (c) 2011 - 2017, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2011 - 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
@@ -538,6 +538,13 @@ SmmPerformanceHandlerEx (
          break;
        }
 
+       //
+       // The AsmLfence() call here is to ensure the previous range/content
+       // checks for the CommBuffer have been completed before calling
+       // CopyMem().
+       //
+       AsmLfence ();
+
        GaugeEntryExArray = (GAUGE_DATA_ENTRY_EX *) (mGaugeData + 1);
 
        for (Index = 0; Index < NumberOfEntries; Index++) {
@@ -650,6 +657,13 @@ SmmPerformanceHandler (
          break;
        }
 
+       //
+       // The AsmLfence() call here is to ensure the previous range/content
+       // checks for the CommBuffer have been completed before calling
+       // CopyMem().
+       //
+       AsmLfence ();
+
        GaugeEntryExArray = (GAUGE_DATA_ENTRY_EX *) (mGaugeData + 1);
 
        for (Index = 0; Index < NumberOfEntries; Index++) {
-- 
2.12.0.windows.1

Re: [PATCH v2 1/2] MdeModulePkg/SmmCorePerfLib: [CVE-2017-5753] Fix bounds check bypass

[Zeng, Star]

Reviewed-by: Star Zeng <star.zeng@intel.com>

-----Original Message-----
From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Hao Wu
Sent: Friday, November 16, 2018 12:13 PM
To: edk2-devel@lists.01.org
Cc: Wu, Hao A <hao.a.wu@intel.com>; Laszlo Ersek <lersek@redhat.com>; Yao, Jiewen <jiewen.yao@intel.com>; Zeng, Star <star.zeng@intel.com>
Subject: [edk2] [PATCH v2 1/2] MdeModulePkg/SmmCorePerfLib: [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 SmmCorePerformanceLib and insert AsmLfence API to mitigate the bounds check bypass issue.

For SMI handler SmmPerformanceHandlerEx():

Under "case SMM_PERF_FUNCTION_GET_GAUGE_DATA :", 'SmmPerfCommData->LogEntryKey' can be a potential cross boundary access of the 'CommBuffer' (controlled external inputs) during speculative execution. This cross boundary access is then assign to parameter 'LogEntryKey'. And the value of 'LogEntryKey' can be inferred by code:

  CopyMem (
    (UINT8 *) &GaugeDataEx[Index],
    (UINT8 *) &GaugeEntryExArray[LogEntryKey++],
    sizeof (GAUGE_DATA_ENTRY_EX)
    );

One can observe which part of the content within 'GaugeEntryExArray' was brought into cache to possibly reveal the value of 'LogEntryKey'.

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

And there is 1 similar case for SMI handler SmmPerformanceHandler() as well. This commit also handles it.

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: Star Zeng <star.zeng@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
---
 MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c b/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c
index cd1f1a5d5f..63c1eea3a2 100644
--- a/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c
+++ b/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c
@@ -16,7 +16,7 @@
 
  SmmPerformanceHandlerEx(), SmmPerformanceHandler() will receive untrusted input and do basic validation.
 
-Copyright (c) 2011 - 2017, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2011 - 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 @@ -538,6 +538,13 @@ SmmPerformanceHandlerEx (
          break;
        }
 
+       //
+       // The AsmLfence() call here is to ensure the previous range/content
+       // checks for the CommBuffer have been completed before calling
+       // CopyMem().
+       //
+       AsmLfence ();
+
        GaugeEntryExArray = (GAUGE_DATA_ENTRY_EX *) (mGaugeData + 1);
 
        for (Index = 0; Index < NumberOfEntries; Index++) { @@ -650,6 +657,13 @@ SmmPerformanceHandler (
          break;
        }
 
+       //
+       // The AsmLfence() call here is to ensure the previous range/content
+       // checks for the CommBuffer have been completed before calling
+       // CopyMem().
+       //
+       AsmLfence ();
+
        GaugeEntryExArray = (GAUGE_DATA_ENTRY_EX *) (mGaugeData + 1);
 
        for (Index = 0; Index < NumberOfEntries; Index++) {
--
2.12.0.windows.1

_______________________________________________
edk2-devel mailing list
edk2-devel@lists.01.org
https://lists.01.org/mailman/listinfo/edk2-devel

Re: [PATCH v2 1/2] MdeModulePkg/SmmCorePerfLib: [CVE-2017-5753] Fix bounds check bypass

[Gao, Liming]

Hao:
  In previous discussion, the suggested subject style is MdeModulePkg/SmmCorePerfLib: Fix bounds check bypass(CVE-2017-5753). 

Thanks
Liming
> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Hao Wu
> Sent: Friday, November 16, 2018 12:13 PM
> To: edk2-devel@lists.01.org
> Cc: Wu, Hao A <hao.a.wu@intel.com>; Laszlo Ersek <lersek@redhat.com>; Yao, Jiewen <jiewen.yao@intel.com>; Zeng, Star
> <star.zeng@intel.com>
> Subject: [edk2] [PATCH v2 1/2] MdeModulePkg/SmmCorePerfLib: [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
> SmmCorePerformanceLib and insert AsmLfence API to mitigate the bounds
> check bypass issue.
> 
> For SMI handler SmmPerformanceHandlerEx():
> 
> Under "case SMM_PERF_FUNCTION_GET_GAUGE_DATA :",
> 'SmmPerfCommData->LogEntryKey' can be a potential cross boundary access of
> the 'CommBuffer' (controlled external inputs) during speculative
> execution. This cross boundary access is then assign to parameter
> 'LogEntryKey'. And the value of 'LogEntryKey' can be inferred by code:
> 
>   CopyMem (
>     (UINT8 *) &GaugeDataEx[Index],
>     (UINT8 *) &GaugeEntryExArray[LogEntryKey++],
>     sizeof (GAUGE_DATA_ENTRY_EX)
>     );
> 
> One can observe which part of the content within 'GaugeEntryExArray' was
> brought into cache to possibly reveal the value of 'LogEntryKey'.
> 
> Hence, this commit adds a AsmLfence() after the boundary/range checks of
> 'CommBuffer' to prevent the speculative execution.
> 
> And there is 1 similar case for SMI handler SmmPerformanceHandler() as
> well. This commit also handles it.
> 
> 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-vuln
> erabilities.pdf
> 
> Cc: Star Zeng <star.zeng@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Hao Wu <hao.a.wu@intel.com>
> ---
>  MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c
> b/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c
> index cd1f1a5d5f..63c1eea3a2 100644
> --- a/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c
> +++ b/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLib.c
> @@ -16,7 +16,7 @@
> 
>   SmmPerformanceHandlerEx(), SmmPerformanceHandler() will receive untrusted input and do basic validation.
> 
> -Copyright (c) 2011 - 2017, Intel Corporation. All rights reserved.<BR>
> +Copyright (c) 2011 - 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
> @@ -538,6 +538,13 @@ SmmPerformanceHandlerEx (
>           break;
>         }
> 
> +       //
> +       // The AsmLfence() call here is to ensure the previous range/content
> +       // checks for the CommBuffer have been completed before calling
> +       // CopyMem().
> +       //
> +       AsmLfence ();
> +
>         GaugeEntryExArray = (GAUGE_DATA_ENTRY_EX *) (mGaugeData + 1);
> 
>         for (Index = 0; Index < NumberOfEntries; Index++) {
> @@ -650,6 +657,13 @@ SmmPerformanceHandler (
>           break;
>         }
> 
> +       //
> +       // The AsmLfence() call here is to ensure the previous range/content
> +       // checks for the CommBuffer have been completed before calling
> +       // CopyMem().
> +       //
> +       AsmLfence ();
> +
>         GaugeEntryExArray = (GAUGE_DATA_ENTRY_EX *) (mGaugeData + 1);
> 
>         for (Index = 0; Index < NumberOfEntries; Index++) {
> --
> 2.12.0.windows.1
> 
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel

Re: [PATCH v2 1/2] MdeModulePkg/SmmCorePerfLib: [CVE-2017-5753] Fix bounds check bypass

[Wu, Hao A]

Got it.
Since the patches have already been checked in. I will follow this style next
time.

Best Regards,
Hao Wu


> -----Original Message-----
> From: Gao, Liming
> Sent: Wednesday, November 21, 2018 2:16 PM
> To: Wu, Hao A; edk2-devel@lists.01.org
> Cc: Wu, Hao A; Laszlo Ersek; Yao, Jiewen; Zeng, Star
> Subject: RE: [edk2] [PATCH v2 1/2] MdeModulePkg/SmmCorePerfLib: [CVE-
> 2017-5753] Fix bounds check bypass
> 
> Hao:
>   In previous discussion, the suggested subject style is
> MdeModulePkg/SmmCorePerfLib: Fix bounds check bypass(CVE-2017-5753).
> 
> Thanks
> Liming
> > -----Original Message-----
> > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> Hao Wu
> > Sent: Friday, November 16, 2018 12:13 PM
> > To: edk2-devel@lists.01.org
> > Cc: Wu, Hao A <hao.a.wu@intel.com>; Laszlo Ersek <lersek@redhat.com>;
> Yao, Jiewen <jiewen.yao@intel.com>; Zeng, Star
> > <star.zeng@intel.com>
> > Subject: [edk2] [PATCH v2 1/2] MdeModulePkg/SmmCorePerfLib: [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
> > SmmCorePerformanceLib and insert AsmLfence API to mitigate the
> bounds
> > check bypass issue.
> >
> > For SMI handler SmmPerformanceHandlerEx():
> >
> > Under "case SMM_PERF_FUNCTION_GET_GAUGE_DATA :",
> > 'SmmPerfCommData->LogEntryKey' can be a potential cross boundary
> access of
> > the 'CommBuffer' (controlled external inputs) during speculative
> > execution. This cross boundary access is then assign to parameter
> > 'LogEntryKey'. And the value of 'LogEntryKey' can be inferred by code:
> >
> >   CopyMem (
> >     (UINT8 *) &GaugeDataEx[Index],
> >     (UINT8 *) &GaugeEntryExArray[LogEntryKey++],
> >     sizeof (GAUGE_DATA_ENTRY_EX)
> >     );
> >
> > One can observe which part of the content within 'GaugeEntryExArray' was
> > brought into cache to possibly reveal the value of 'LogEntryKey'.
> >
> > Hence, this commit adds a AsmLfence() after the boundary/range checks
> of
> > 'CommBuffer' to prevent the speculative execution.
> >
> > And there is 1 similar case for SMI handler SmmPerformanceHandler() as
> > well. This commit also handles it.
> >
> > 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-
> vuln
> > erabilities.pdf
> >
> > Cc: Star Zeng <star.zeng@intel.com>
> > Cc: Jiewen Yao <jiewen.yao@intel.com>
> > Cc: Laszlo Ersek <lersek@redhat.com>
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Hao Wu <hao.a.wu@intel.com>
> > ---
> >
> MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformanceLi
> b.c | 16 +++++++++++++++-
> >  1 file changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git
> a/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformance
> Lib.c
> >
> b/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformance
> Lib.c
> > index cd1f1a5d5f..63c1eea3a2 100644
> > ---
> a/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformance
> Lib.c
> > +++
> b/MdeModulePkg/Library/SmmCorePerformanceLib/SmmCorePerformance
> Lib.c
> > @@ -16,7 +16,7 @@
> >
> >   SmmPerformanceHandlerEx(), SmmPerformanceHandler() will receive
> untrusted input and do basic validation.
> >
> > -Copyright (c) 2011 - 2017, Intel Corporation. All rights reserved.<BR>
> > +Copyright (c) 2011 - 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
> > @@ -538,6 +538,13 @@ SmmPerformanceHandlerEx (
> >           break;
> >         }
> >
> > +       //
> > +       // The AsmLfence() call here is to ensure the previous range/content
> > +       // checks for the CommBuffer have been completed before calling
> > +       // CopyMem().
> > +       //
> > +       AsmLfence ();
> > +
> >         GaugeEntryExArray = (GAUGE_DATA_ENTRY_EX *) (mGaugeData + 1);
> >
> >         for (Index = 0; Index < NumberOfEntries; Index++) {
> > @@ -650,6 +657,13 @@ SmmPerformanceHandler (
> >           break;
> >         }
> >
> > +       //
> > +       // The AsmLfence() call here is to ensure the previous range/content
> > +       // checks for the CommBuffer have been completed before calling
> > +       // CopyMem().
> > +       //
> > +       AsmLfence ();
> > +
> >         GaugeEntryExArray = (GAUGE_DATA_ENTRY_EX *) (mGaugeData + 1);
> >
> >         for (Index = 0; Index < NumberOfEntries; Index++) {
> > --
> > 2.12.0.windows.1
> >
> > _______________________________________________
> > edk2-devel mailing list
> > edk2-devel@lists.01.org
> > https://lists.01.org/mailman/listinfo/edk2-devel

[PATCH v2 2/2] SecurityPkg/OpalPWSupportLib: [CVE-2017-5753] Fix bounds check bypass

[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
OpalPasswordSupportLib and insert AsmLfence API to mitigate the bounds
check bypass issue.

For SMI handler SmmOpalPasswordHandler():

Under "case SMM_FUNCTION_SET_OPAL_PASSWORD:",
'&DeviceBuffer->OpalDevicePath' can points to a potential cross boundary
access of the 'CommBuffer' (controlled external inputs) during speculative
execution. This cross boundary access pointer is later passed as parameter
'DevicePath' into function OpalSavePasswordToSmm().

Within function OpalSavePasswordToSmm(), 'DevicePathLen' is an access to
the content in 'DevicePath' and can be inferred by code:
"CompareMem (&List->OpalDevicePath, DevicePath, DevicePathLen)". One can
observe which part of the content within either '&List->OpalDevicePath' or
'DevicePath' was brought into cache to possibly reveal the value of
'DevicePathLen'.

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: Star Zeng <star.zeng@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
---
 SecurityPkg/Library/OpalPasswordSupportLib/OpalPasswordSupportLib.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/SecurityPkg/Library/OpalPasswordSupportLib/OpalPasswordSupportLib.c b/SecurityPkg/Library/OpalPasswordSupportLib/OpalPasswordSupportLib.c
index e377e9ca79..1c3bfffb86 100644
--- a/SecurityPkg/Library/OpalPasswordSupportLib/OpalPasswordSupportLib.c
+++ b/SecurityPkg/Library/OpalPasswordSupportLib/OpalPasswordSupportLib.c
@@ -1,7 +1,7 @@
 /** @file
   Implementation of Opal password support library.
 
-Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2016 - 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
@@ -706,6 +706,11 @@ SmmOpalPasswordHandler (
         Status = EFI_INVALID_PARAMETER;
         goto EXIT;
       }
+      //
+      // The AsmLfence() call here is to ensure the above range checks for the
+      // CommBuffer have been completed before calling into OpalSavePasswordToSmm().
+      //
+      AsmLfence ();
 
       Status = OpalSavePasswordToSmm (&DeviceBuffer->OpalDevicePath, DeviceBuffer->Password, DeviceBuffer->PasswordLength);
       break;
-- 
2.12.0.windows.1

Re: [PATCH v2 2/2] SecurityPkg/OpalPWSupportLib: [CVE-2017-5753] Fix bounds check bypass

[Dong, Eric]

Reviewed-by: Eric Dong <eric.dong@intel.com>

> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> Hao Wu
> Sent: Friday, November 16, 2018 12:13 PM
> To: edk2-devel@lists.01.org
> Cc: Wu, Hao A <hao.a.wu@intel.com>; Laszlo Ersek <lersek@redhat.com>;
> Yao, Jiewen <jiewen.yao@intel.com>; Zhang, Chao B
> <chao.b.zhang@intel.com>; Zeng, Star <star.zeng@intel.com>
> Subject: [edk2] [PATCH v2 2/2] SecurityPkg/OpalPWSupportLib: [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
> OpalPasswordSupportLib and insert AsmLfence API to mitigate the bounds
> check bypass issue.
> 
> For SMI handler SmmOpalPasswordHandler():
> 
> Under "case SMM_FUNCTION_SET_OPAL_PASSWORD:",
> '&DeviceBuffer->OpalDevicePath' can points to a potential cross boundary
> access of the 'CommBuffer' (controlled external inputs) during speculative
> execution. This cross boundary access pointer is later passed as parameter
> 'DevicePath' into function OpalSavePasswordToSmm().
> 
> Within function OpalSavePasswordToSmm(), 'DevicePathLen' is an access to
> the content in 'DevicePath' and can be inferred by code:
> "CompareMem (&List->OpalDevicePath, DevicePath, DevicePathLen)". One
> can
> observe which part of the content within either '&List->OpalDevicePath' or
> 'DevicePath' was brought into cache to possibly reveal the value of
> 'DevicePathLen'.
> 
> 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: Star Zeng <star.zeng@intel.com>
> Cc: Chao Zhang <chao.b.zhang@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Hao Wu <hao.a.wu@intel.com>
> ---
>  SecurityPkg/Library/OpalPasswordSupportLib/OpalPasswordSupportLib.c | 7
> ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git
> a/SecurityPkg/Library/OpalPasswordSupportLib/OpalPasswordSupportLib.c
> b/SecurityPkg/Library/OpalPasswordSupportLib/OpalPasswordSupportLib.c
> index e377e9ca79..1c3bfffb86 100644
> ---
> a/SecurityPkg/Library/OpalPasswordSupportLib/OpalPasswordSupportLib.c
> +++
> b/SecurityPkg/Library/OpalPasswordSupportLib/OpalPasswordSupportLib.c
> @@ -1,7 +1,7 @@
>  /** @file
>    Implementation of Opal password support library.
> 
> -Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
> +Copyright (c) 2016 - 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
> @@ -706,6 +706,11 @@ SmmOpalPasswordHandler (
>          Status = EFI_INVALID_PARAMETER;
>          goto EXIT;
>        }
> +      //
> +      // The AsmLfence() call here is to ensure the above range checks for the
> +      // CommBuffer have been completed before calling into
> OpalSavePasswordToSmm().
> +      //
> +      AsmLfence ();
> 
>        Status = OpalSavePasswordToSmm (&DeviceBuffer->OpalDevicePath,
> DeviceBuffer->Password, DeviceBuffer->PasswordLength);
>        break;
> --
> 2.12.0.windows.1
> 
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