Fix type casting issue when calculating pointers offset

Cc: Wu Hao <hao.a.wu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Chao Zhang <chao.b.zhang@intel.com>
---
 SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c b/SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c
index 6eb62ae..c3cee83 100644
--- a/SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c
+++ b/SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c
@@ -543,7 +543,7 @@ UpdatePossibleResource (
   //
   DataPtr += 2;
   if (DataPtr < DataEndPtr) {
-    SetMem(DataPtr, (UINTN)(DataEndPtr - DataPtr), AML_NOOP_OP);
+    SetMem(DataPtr, (UINTN)DataEndPtr - (UINTN)DataPtr, AML_NOOP_OP);
   }
 
   return EFI_SUCCESS;
-- 
1.9.5.msysgit.1

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Hi Chao,

The change is good to me. How about changing the commit title and body
into:


SecurityPkg/Tcg2Smm: Refine type cast for pointer subtraction

Since the pointer subtraction here is not performed by pointers to
elements of the same array object. This might lead to potential issues,
such behavior is undefined according to C11 standard.

Refine the pointer subtraction expressions by casting each pointer to
UINTN first and then perform the subtraction.


With the commit message change:
Reviewed-by: Hao Wu <hao.a.wu@intel.com>


Best Regards,
Hao Wu

> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> Zhang, Chao B
> Sent: Thursday, February 08, 2018 2:25 PM
> To: edk2-devel@lists.01.org
> Cc: Wu, Hao A; Zhang, Chao B
> Subject: [edk2] [PATCH] SecurityPkg: Tcg2Smm: Fix type casting issue
> 
> Fix type casting issue when calculating pointers offset
> 
> Cc: Wu Hao <hao.a.wu@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Chao Zhang <chao.b.zhang@intel.com>
> ---
>  SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c
> b/SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c
> index 6eb62ae..c3cee83 100644
> --- a/SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c
> +++ b/SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c
> @@ -543,7 +543,7 @@ UpdatePossibleResource (
>    //
>    DataPtr += 2;
>    if (DataPtr < DataEndPtr) {
> -    SetMem(DataPtr, (UINTN)(DataEndPtr - DataPtr), AML_NOOP_OP);
> +    SetMem(DataPtr, (UINTN)DataEndPtr - (UINTN)DataPtr, AML_NOOP_OP);
>    }
> 
>    return EFI_SUCCESS;
> --
> 1.9.5.msysgit.1
> 
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel
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