[edk2-devel] [PATCH] SecurityPkg: Initailize variable Status before it is consumed.

[Laszlo Ersek]

On 08/31/20 10:15, Zhiguang Liu wrote:
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2945
> 
> Cc: Jiewen Yao <jiewen.yao at intel.com>
> Cc: Jian J Wang <jian.j.wang at intel.com>
> Cc: Qi Zhang <qi1.zhang at intel.com>
> Cc: Rahul Kumar <rahul1.kumar at intel.com>
> Signed-off-by: Zhiguang Liu <zhiguang.liu at intel.com>
> ---
>  SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.c b/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.c
> index 0e770f4485..5e883f0cc5 100644
> --- a/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.c
> +++ b/SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.c
> @@ -449,6 +449,7 @@ HashLogExtendEvent (
>    EFI_STATUS                        Status;
>    TPML_DIGEST_VALUES                DigestList;
>  
> +  Status = EFI_SUCCESS;
>    if (GetFirstGuidHob (&gTpmErrorHobGuid) != NULL) {
>      return EFI_DEVICE_ERROR;
>    }
> 

I agree that there is a path in the code where Status is read without
having been set.

It seems that using EFI_SUCCESS as default value makes sense (assuming
the LogHashEvent() call is the important one). I'll let SecurityPkg
maintainers decide about this.

I think it would be nicer to set Status to EFI_SUCCESS either on the
(currently missing) "else" branch, or else just before the
EDKII_TCG_PRE_HASH check. In particular, setting Status so early that we
may still exit with EFI_DEVICE_ERROR is wasteful. So at least I'd move
the assignment past the "return EFI_DEVICE_ERROR" statement.

But... it's late. I agree that this patch qualifies for the stable tag.
So I'm not asking for a repost. I just wish more thought had been given
to the placement of the assignment.

Laszlo


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