Re: [edk2-devel] [PATCH 1/1] IntelFsp2Pkg/Library/BaseFspCommonLib: Fix OVERRUN Coverity issue

["Chiu, Chasel" <chasel.chiu@intel.com>]

That’s good suggestion Pedro!
Ranbir, would you like me to modify your patch to "return 0" during merging?

Thanks,
Chasel


> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Pedro
> Falcato
> Sent: Friday, May 19, 2023 5:29 AM
> To: devel@edk2.groups.io; rsingh@ventanamicro.com
> Cc: Chiu, Chasel <chasel.chiu@intel.com>; Desimone, Nathaniel L
> <nathaniel.l.desimone@intel.com>; Zeng, Star <star.zeng@intel.com>; Ranbir
> Singh <Ranbir.Singh3@dell.com>
> Subject: Re: [edk2-devel] [PATCH 1/1] IntelFsp2Pkg/Library/BaseFspCommonLib:
> Fix OVERRUN Coverity issue
> 
> On Thu, May 18, 2023 at 4:16 PM Ranbir Singh <rsingh@ventanamicro.com>
> wrote:
> >
> > FspData->PerfIdx is getting increased for every call unconditionally
> > in the function SetFspMeasurePoint and hence memory access can happen
> > for out of bound FspData->PerfData[] array entries also.
> >
> > Example -
> >    FspData->PerfData is an array of 32 UINT64 entries. Assume a call
> >    is made to SetFspMeasurePoint function when the FspData->PerfIdx
> >    last value is 31. It gets incremented to 32 at line 400.
> >    Any subsequent call to SetFspMeasurePoint functions leads to
> >    FspData->PerfData[32] getting accessed which is out of the PerfData
> >    array as well as the FSP_GLOBAL_DATA structure boundary.
> >
> > Hence keep array access and index increment inside if block only and
> > return invalid performance timestamp when PerfIdx is invalid.
> >
> > Cc: Chasel Chiu <chasel.chiu@intel.com>
> > Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
> > Cc: Star Zeng <star.zeng@intel.com>
> > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4200
> > Signed-off-by: Ranbir Singh <Ranbir.Singh3@Dell.com>
> > Signed-off-by: Ranbir Singh <rsingh@ventanamicro.com>
> > ---
> >  IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c
> > b/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c
> > index a22b0e7825ad..cda2a7b2478e 100644
> > --- a/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c
> > +++ b/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c
> > @@ -377,7 +377,8 @@ GetFspSiliconInitUpdDataPointer (
> >
> >    @param[in] Id       Measurement point ID.
> >
> > -  @return performance timestamp.
> > +  @return performance timestamp if current PerfIdx is valid,
> > +          else return 0 as invalid performance timestamp
> >  **/
> >  UINT64
> >  EFIAPI
> > @@ -395,9 +396,10 @@ SetFspMeasurePoint (
> >    if (FspData->PerfIdx < sizeof (FspData->PerfData) / sizeof (FspData-
> >PerfData[0])) {
> >      FspData->PerfData[FspData->PerfIdx]                  = AsmReadTsc ();
> >      ((UINT8 *)(&FspData->PerfData[FspData->PerfIdx]))[7] = Id;
> > +    return FspData->PerfData[(FspData->PerfIdx)++];
> >    }
> >
> > -  return FspData->PerfData[(FspData->PerfIdx)++];
> > +  return (UINT64)0x0000000000000000;
> 
> return 0;
> 
> Works just as well. You also don't need a cast.
> 
> https://godbolt.org/z/e5vvGcWWo
> 
> --
> Pedro
> 
> 
> 
>