Re: [edk2-devel] [PATCH] UefiCpuPkg RegisterCpuFeaturesLib: NumberOfCpus may be uninitialized

["Zeng, Star" <star.zeng@intel.com>]

> -----Original Message-----
> From: Laszlo Ersek <lersek@redhat.com>
> Sent: Thursday, January 21, 2021 10:38 PM
> To: devel@edk2.groups.io; Zeng, Star <star.zeng@intel.com>
> Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>
> Subject: Re: [edk2-devel] [PATCH] UefiCpuPkg RegisterCpuFeaturesLib:
> NumberOfCpus may be uninitialized
> 
> On 01/21/21 10:39, Zeng, Star wrote:
> > NumberOfCpus local variable in GetAcpiCpuData will be uninitialized
> > when CpuS3DataDxe runs before DxeRegisterCpuFeaturesLib (linked by
> > CpuFeaturesDxe) because there is no code to initialize it at
> > (AcpiCpuData != NULL) execution path.
> >
> > The issue is exposed after cefad282fb31aff3e1a6dcbd368cbbffc3fce900
> > and 38ee7bafa72f58982f99ac6f61eef160f80bad69.
> > There was negligence in that code review.
> > One further topic may be "Could EDK2 CI be enhanced to catch this kind
> > of uninitialized local variable case?". :)
> >
> > This patch fixes this regression issue.
> >
> > Cc: Eric Dong <eric.dong@intel.com>
> > Cc: Ray Ni <ray.ni@intel.com>
> > Cc: Laszlo Ersek <lersek@redhat.com>
> > Signed-off-by: Star Zeng <star.zeng@intel.com>
> > ---
> >  .../Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c      | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git
> > a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
> > b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
> > index 7bb92404027f..60daa5cc87f0 100644
> > ---
> > a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
> > +++ b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib
> > +++ .c
> > @@ -957,6 +957,7 @@ GetAcpiCpuData (
> >      //
> >      // Allocate buffer for empty RegisterTable and PreSmmInitRegisterTable
> for all CPUs
> >      //
> > +    NumberOfCpus = AcpiCpuData->NumberOfCpus;
> >      TableSize = 2 * NumberOfCpus * sizeof (CPU_REGISTER_TABLE);
> >      RegisterTable  = AllocatePages (EFI_SIZE_TO_PAGES (TableSize));
> >      ASSERT (RegisterTable != NULL);
> >
> 
> Merged as commit 6c5801be6ef3, via
> <https://github.com/tianocore/edk2/pull/1380>.
> 
> I've picked up Ray's R-b from the detached message
> <https://edk2.groups.io/g/devel/message/70615>.
> 
> I've also updated the original ticket:
> <https://bugzilla.tianocore.org/show_bug.cgi?id=3159>.
> 
> Thanks & sorry about the regression,
> Laszlo

No worry, it was my negligence for the original code review series.
Fortunately, we catch it quickly. 😊

Star