Re: [edk2] [PATCH] MdePkg/SafeString: Directly return when length of source string is 0

2018-02-05 Thread Ni, Ruiyu 

On 2/5/2018 11:55 AM, Yao, Jiewen wrote:

Thanks to catch this.

The root-cause of the failure is below line:

   SourceLen = StrnLenS (Source, DestMax);

We should only limit the Source string access within Length, not DestMax, if 
Length is smaller than DestMax.

0 is just one special case. Length might be 1, 2, or 3 and it triggers same 
failure.

So only checking 0 is not enough.

Reviewed the code with Ruiyu. We think using below check seems better way to 
handle all cases.

   SourceLen = StrnLenS (Source, MIN(DestMax, Length));

The check for 0 is not needed.


Patch v2 is sent out.



Thank you
Yao Jiewen


-Original Message-
From: Laszlo Ersek [mailto:ler...@redhat.com]
Sent: Friday, February 2, 2018 9:43 PM
To: Ni, Ruiyu ; edk2-devel@lists.01.org
Cc: Yao, Jiewen ; Gao, Liming 
Subject: Re: [edk2] [PATCH] MdePkg/SafeString: Directly return when length of
source string is 0

On 02/02/18 11:47, Ruiyu Ni wrote:

Today's implementation of [Ascii]StrnCpyS/[Ascii]StrnCatS doesn't
directly return the the length of source string is 0.

When length of source string is 0, it means the Source points to
a memory that shouldn't be deferenced at all.
So it's not proper to call StrnLenS() in such situation.
In a pool guard enabled environment, when using shell to edit an
existing file which contains empty line, the page fault is met.

The patch fixes the four library functions to align to the behavior
of non-safe version: directly return when length of source string
is 0.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ruiyu Ni 
Cc: Jiewen Yao 
Cc: Liming Gao 
Cc: Jian J Wang 
---
  MdePkg/Library/BaseLib/SafeString.c | 18 +-
  1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/MdePkg/Library/BaseLib/SafeString.c

b/MdePkg/Library/BaseLib/SafeString.c

index 68c33e9b7b..fed818ef33 100644
--- a/MdePkg/Library/BaseLib/SafeString.c
+++ b/MdePkg/Library/BaseLib/SafeString.c
@@ -1,7 +1,7 @@
  /** @file
Safe String functions.

-  Copyright (c) 2014 - 2017, Intel Corporation. All rights reserved.
+  Copyright (c) 2014 - 2018, Intel Corporation. All rights reserved.
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

@@ -317,6 +317,10 @@ StrnCpyS (
  {
UINTNSourceLen;

+  if (Length == 0) {
+return RETURN_SUCCESS;
+  }
+
ASSERT (((UINTN) Destination & BIT0) == 0);
ASSERT (((UINTN) Source & BIT0) == 0);

@@ -515,6 +519,10 @@ StrnCatS (
UINTN   CopyLen;
UINTN   SourceLen;

+  if (Length == 0) {
+return RETURN_SUCCESS;
+  }
+
ASSERT (((UINTN) Destination & BIT0) == 0);
ASSERT (((UINTN) Source & BIT0) == 0);

@@ -1894,6 +1902,10 @@ AsciiStrnCpyS (
  {
UINTNSourceLen;

+  if (Length == 0) {
+return RETURN_SUCCESS;
+  }
+
//
// 1. Neither Destination nor Source shall be a null pointer.
//
@@ -2082,6 +2094,10 @@ AsciiStrnCatS (
UINTN   CopyLen;
UINTN   SourceLen;

+  if (Length == 0) {
+return RETURN_SUCCESS;
+  }
+
//
// Let CopyLen denote the value DestMax - AsciiStrnLenS(Destination,

DestMax) upon entry to AsciiStrnCatS.

//



Reviewed-by: Laszlo Ersek 



--
Thanks,
Ray
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Re: [edk2] [PATCH] MdePkg/SafeString: Directly return when length of source string is 0

2018-02-04 Thread Yao, Jiewen 
Thanks to catch this.

The root-cause of the failure is below line:

  SourceLen = StrnLenS (Source, DestMax);

We should only limit the Source string access within Length, not DestMax, if 
Length is smaller than DestMax.

0 is just one special case. Length might be 1, 2, or 3 and it triggers same 
failure.

So only checking 0 is not enough.

Reviewed the code with Ruiyu. We think using below check seems better way to 
handle all cases.

  SourceLen = StrnLenS (Source, MIN(DestMax, Length));

The check for 0 is not needed.

Thank you
Yao Jiewen

> -Original Message-
> From: Laszlo Ersek [mailto:ler...@redhat.com]
> Sent: Friday, February 2, 2018 9:43 PM
> To: Ni, Ruiyu ; edk2-devel@lists.01.org
> Cc: Yao, Jiewen ; Gao, Liming 
> Subject: Re: [edk2] [PATCH] MdePkg/SafeString: Directly return when length of
> source string is 0
> 
> On 02/02/18 11:47, Ruiyu Ni wrote:
> > Today's implementation of [Ascii]StrnCpyS/[Ascii]StrnCatS doesn't
> > directly return the the length of source string is 0.
> >
> > When length of source string is 0, it means the Source points to
> > a memory that shouldn't be deferenced at all.
> > So it's not proper to call StrnLenS() in such situation.
> > In a pool guard enabled environment, when using shell to edit an
> > existing file which contains empty line, the page fault is met.
> >
> > The patch fixes the four library functions to align to the behavior
> > of non-safe version: directly return when length of source string
> > is 0.
> >
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Ruiyu Ni 
> > Cc: Jiewen Yao 
> > Cc: Liming Gao 
> > Cc: Jian J Wang 
> > ---
> >  MdePkg/Library/BaseLib/SafeString.c | 18 +-
> >  1 file changed, 17 insertions(+), 1 deletion(-)
> >
> > diff --git a/MdePkg/Library/BaseLib/SafeString.c
> b/MdePkg/Library/BaseLib/SafeString.c
> > index 68c33e9b7b..fed818ef33 100644
> > --- a/MdePkg/Library/BaseLib/SafeString.c
> > +++ b/MdePkg/Library/BaseLib/SafeString.c
> > @@ -1,7 +1,7 @@
> >  /** @file
> >Safe String functions.
> >
> > -  Copyright (c) 2014 - 2017, Intel Corporation. All rights reserved.
> > +  Copyright (c) 2014 - 2018, Intel Corporation. All rights reserved.
> >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
> > @@ -317,6 +317,10 @@ StrnCpyS (
> >  {
> >UINTNSourceLen;
> >
> > +  if (Length == 0) {
> > +return RETURN_SUCCESS;
> > +  }
> > +
> >ASSERT (((UINTN) Destination & BIT0) == 0);
> >ASSERT (((UINTN) Source & BIT0) == 0);
> >
> > @@ -515,6 +519,10 @@ StrnCatS (
> >UINTN   CopyLen;
> >UINTN   SourceLen;
> >
> > +  if (Length == 0) {
> > +return RETURN_SUCCESS;
> > +  }
> > +
> >ASSERT (((UINTN) Destination & BIT0) == 0);
> >ASSERT (((UINTN) Source & BIT0) == 0);
> >
> > @@ -1894,6 +1902,10 @@ AsciiStrnCpyS (
> >  {
> >UINTNSourceLen;
> >
> > +  if (Length == 0) {
> > +return RETURN_SUCCESS;
> > +  }
> > +
> >//
> >// 1. Neither Destination nor Source shall be a null pointer.
> >//
> > @@ -2082,6 +2094,10 @@ AsciiStrnCatS (
> >UINTN   CopyLen;
> >UINTN   SourceLen;
> >
> > +  if (Length == 0) {
> > +return RETURN_SUCCESS;
> > +  }
> > +
> >//
> >// Let CopyLen denote the value DestMax - AsciiStrnLenS(Destination,
> DestMax) upon entry to AsciiStrnCatS.
> >//
> >
> 
> Reviewed-by: Laszlo Ersek 
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Re: [edk2] [PATCH] MdePkg/SafeString: Directly return when length of source string is 0

2018-02-04 Thread Wang, Jian J 

Reviewed-by: Jian J Wang 

> -Original Message-
> From: Ni, Ruiyu
> Sent: Friday, February 02, 2018 6:48 PM
> To: edk2-devel@lists.01.org
> Cc: Yao, Jiewen ; Gao, Liming ;
> Wang, Jian J 
> Subject: [PATCH] MdePkg/SafeString: Directly return when length of source
> string is 0
> 
> Today's implementation of [Ascii]StrnCpyS/[Ascii]StrnCatS doesn't
> directly return the the length of source string is 0.
> 
> When length of source string is 0, it means the Source points to
> a memory that shouldn't be deferenced at all.
> So it's not proper to call StrnLenS() in such situation.
> In a pool guard enabled environment, when using shell to edit an
> existing file which contains empty line, the page fault is met.
> 
> The patch fixes the four library functions to align to the behavior
> of non-safe version: directly return when length of source string
> is 0.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ruiyu Ni 
> Cc: Jiewen Yao 
> Cc: Liming Gao 
> Cc: Jian J Wang 
> ---
>  MdePkg/Library/BaseLib/SafeString.c | 18 +-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/MdePkg/Library/BaseLib/SafeString.c
> b/MdePkg/Library/BaseLib/SafeString.c
> index 68c33e9b7b..fed818ef33 100644
> --- a/MdePkg/Library/BaseLib/SafeString.c
> +++ b/MdePkg/Library/BaseLib/SafeString.c
> @@ -1,7 +1,7 @@
>  /** @file
>Safe String functions.
> 
> -  Copyright (c) 2014 - 2017, Intel Corporation. All rights reserved.
> +  Copyright (c) 2014 - 2018, Intel Corporation. All rights reserved.
>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
> @@ -317,6 +317,10 @@ StrnCpyS (
>  {
>UINTNSourceLen;
> 
> +  if (Length == 0) {
> +return RETURN_SUCCESS;
> +  }
> +
>ASSERT (((UINTN) Destination & BIT0) == 0);
>ASSERT (((UINTN) Source & BIT0) == 0);
> 
> @@ -515,6 +519,10 @@ StrnCatS (
>UINTN   CopyLen;
>UINTN   SourceLen;
> 
> +  if (Length == 0) {
> +return RETURN_SUCCESS;
> +  }
> +
>ASSERT (((UINTN) Destination & BIT0) == 0);
>ASSERT (((UINTN) Source & BIT0) == 0);
> 
> @@ -1894,6 +1902,10 @@ AsciiStrnCpyS (
>  {
>UINTNSourceLen;
> 
> +  if (Length == 0) {
> +return RETURN_SUCCESS;
> +  }
> +
>//
>// 1. Neither Destination nor Source shall be a null pointer.
>//
> @@ -2082,6 +2094,10 @@ AsciiStrnCatS (
>UINTN   CopyLen;
>UINTN   SourceLen;
> 
> +  if (Length == 0) {
> +return RETURN_SUCCESS;
> +  }
> +
>//
>// Let CopyLen denote the value DestMax - AsciiStrnLenS(Destination,
> DestMax) upon entry to AsciiStrnCatS.
>//
> --
> 2.16.1.windows.1

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Re: [edk2] [PATCH] MdePkg/SafeString: Directly return when length of source string is 0

2018-02-02 Thread Laszlo Ersek 
On 02/02/18 11:47, Ruiyu Ni wrote:
> Today's implementation of [Ascii]StrnCpyS/[Ascii]StrnCatS doesn't
> directly return the the length of source string is 0.
> 
> When length of source string is 0, it means the Source points to
> a memory that shouldn't be deferenced at all.
> So it's not proper to call StrnLenS() in such situation.
> In a pool guard enabled environment, when using shell to edit an
> existing file which contains empty line, the page fault is met.
> 
> The patch fixes the four library functions to align to the behavior
> of non-safe version: directly return when length of source string
> is 0.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ruiyu Ni 
> Cc: Jiewen Yao 
> Cc: Liming Gao 
> Cc: Jian J Wang 
> ---
>  MdePkg/Library/BaseLib/SafeString.c | 18 +-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/MdePkg/Library/BaseLib/SafeString.c 
> b/MdePkg/Library/BaseLib/SafeString.c
> index 68c33e9b7b..fed818ef33 100644
> --- a/MdePkg/Library/BaseLib/SafeString.c
> +++ b/MdePkg/Library/BaseLib/SafeString.c
> @@ -1,7 +1,7 @@
>  /** @file
>Safe String functions.
>  
> -  Copyright (c) 2014 - 2017, Intel Corporation. All rights reserved.
> +  Copyright (c) 2014 - 2018, Intel Corporation. All rights reserved.
>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
> @@ -317,6 +317,10 @@ StrnCpyS (
>  {
>UINTNSourceLen;
>  
> +  if (Length == 0) {
> +return RETURN_SUCCESS;
> +  }
> +
>ASSERT (((UINTN) Destination & BIT0) == 0);
>ASSERT (((UINTN) Source & BIT0) == 0);
>  
> @@ -515,6 +519,10 @@ StrnCatS (
>UINTN   CopyLen;
>UINTN   SourceLen;
>  
> +  if (Length == 0) {
> +return RETURN_SUCCESS;
> +  }
> +
>ASSERT (((UINTN) Destination & BIT0) == 0);
>ASSERT (((UINTN) Source & BIT0) == 0);
>  
> @@ -1894,6 +1902,10 @@ AsciiStrnCpyS (
>  {
>UINTNSourceLen;
>  
> +  if (Length == 0) {
> +return RETURN_SUCCESS;
> +  }
> +
>//
>// 1. Neither Destination nor Source shall be a null pointer.
>//
> @@ -2082,6 +2094,10 @@ AsciiStrnCatS (
>UINTN   CopyLen;
>UINTN   SourceLen;
>  
> +  if (Length == 0) {
> +return RETURN_SUCCESS;
> +  }
> +
>//
>// Let CopyLen denote the value DestMax - AsciiStrnLenS(Destination, 
> DestMax) upon entry to AsciiStrnCatS.
>//
> 

Reviewed-by: Laszlo Ersek 
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[edk2] [PATCH] MdePkg/SafeString: Directly return when length of source string is 0

2018-02-02 Thread Ruiyu Ni 
Today's implementation of [Ascii]StrnCpyS/[Ascii]StrnCatS doesn't
directly return the the length of source string is 0.

When length of source string is 0, it means the Source points to
a memory that shouldn't be deferenced at all.
So it's not proper to call StrnLenS() in such situation.
In a pool guard enabled environment, when using shell to edit an
existing file which contains empty line, the page fault is met.

The patch fixes the four library functions to align to the behavior
of non-safe version: directly return when length of source string
is 0.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ruiyu Ni 
Cc: Jiewen Yao 
Cc: Liming Gao 
Cc: Jian J Wang 
---
 MdePkg/Library/BaseLib/SafeString.c | 18 +-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/MdePkg/Library/BaseLib/SafeString.c 
b/MdePkg/Library/BaseLib/SafeString.c
index 68c33e9b7b..fed818ef33 100644
--- a/MdePkg/Library/BaseLib/SafeString.c
+++ b/MdePkg/Library/BaseLib/SafeString.c
@@ -1,7 +1,7 @@
 /** @file
   Safe String functions.
 
-  Copyright (c) 2014 - 2017, Intel Corporation. All rights reserved.
+  Copyright (c) 2014 - 2018, Intel Corporation. All rights reserved.
   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
@@ -317,6 +317,10 @@ StrnCpyS (
 {
   UINTNSourceLen;
 
+  if (Length == 0) {
+return RETURN_SUCCESS;
+  }
+
   ASSERT (((UINTN) Destination & BIT0) == 0);
   ASSERT (((UINTN) Source & BIT0) == 0);
 
@@ -515,6 +519,10 @@ StrnCatS (
   UINTN   CopyLen;
   UINTN   SourceLen;
 
+  if (Length == 0) {
+return RETURN_SUCCESS;
+  }
+
   ASSERT (((UINTN) Destination & BIT0) == 0);
   ASSERT (((UINTN) Source & BIT0) == 0);
 
@@ -1894,6 +1902,10 @@ AsciiStrnCpyS (
 {
   UINTNSourceLen;
 
+  if (Length == 0) {
+return RETURN_SUCCESS;
+  }
+
   //
   // 1. Neither Destination nor Source shall be a null pointer.
   //
@@ -2082,6 +2094,10 @@ AsciiStrnCatS (
   UINTN   CopyLen;
   UINTN   SourceLen;
 
+  if (Length == 0) {
+return RETURN_SUCCESS;
+  }
+
   //
   // Let CopyLen denote the value DestMax - AsciiStrnLenS(Destination, 
DestMax) upon entry to AsciiStrnCatS.
   //
-- 
2.16.1.windows.1

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