Re: [PATCH v2] MdeModulePkg/DxeCore: Please static checker for false report

["Michael D Kinney" <michael.d.kinney@intel.com>]

Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>

> -----Original Message-----
> From: Wu, Hao A
> Sent: Thursday, April 25, 2019 10:39 PM
> To: Ard Biesheuvel <ard.biesheuvel@linaro.org>; Kinney,
> Michael D <michael.d.kinney@intel.com>; Gao, Liming
> <liming.gao@intel.com>; Wang, Jian J
> <jian.j.wang@intel.com>
> Cc: edk2-devel-groups-io <devel@edk2.groups.io>
> Subject: RE: [PATCH v2] MdeModulePkg/DxeCore: Please
> static checker for false report
> 
> > -----Original Message-----
> > From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
> > Sent: Wednesday, April 24, 2019 3:07 PM
> > To: Wu, Hao A
> > Cc: edk2-devel-groups-io; Kinney, Michael D; Gao,
> Liming; Wang, Jian J
> > Subject: Re: [PATCH v2] MdeModulePkg/DxeCore: Please
> static checker for
> > false report
> >
> > On Wed, 24 Apr 2019 at 07:05, Hao Wu
> <hao.a.wu@intel.com> wrote:
> > >
> > > After commit 57df17fe26, some static check reports
> suspicous NULL pointer
> > > deference at line:
> > >
> > >   Entry->MachineType = Entry->Emulator->MachineType;
> > >                        ^^^^^^^^^^^^^^^
> > >
> > > within function PeCoffEmuProtocolNotify().
> > >
> > > However, 'Entry->Emulator' is guaranteed to have a
> non-NULL value when
> > > previous call to the CoreHandleProtocol() returns
> EFI_SUCCESS.
> > >
> > > This commit will re-write the return status check for
> CoreHandleProtocol()
> > > to add explicit NULL pointer check for protocol
> instance pointer.
> > >
> > > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > > Cc: Michael D Kinney <michael.d.kinney@intel.com>
> > > Cc: Liming Gao <liming.gao@intel.com>
> > > Cc: Jian J Wang <jian.j.wang@intel.com>
> > > Signed-off-by: Hao Wu <hao.a.wu@intel.com>
> >
> > Again, I think it is rather unfortunate that we need
> code changes such
> > as this one just to remove warnings from a flawed
> static analyzer. But
> > the change looks correct to me, so
> >
> > Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> 
> Thanks Ard,
> 
> Hello Mike, Liming and Jian,
> 
> Do you have additional feedbacks on this patch?
> If not, I plan to push it with the 'Ack' tag from Ard.
> 
> Best Regards,
> Hao Wu
> 
> >
> > > ---
> > >  MdeModulePkg/Core/Dxe/Image/Image.c | 23
> ++++++++++++--------
> > >  1 file changed, 14 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/MdeModulePkg/Core/Dxe/Image/Image.c
> > b/MdeModulePkg/Core/Dxe/Image/Image.c
> > > index 08306a73fd..de5b8bed27 100644
> > > --- a/MdeModulePkg/Core/Dxe/Image/Image.c
> > > +++ b/MdeModulePkg/Core/Dxe/Image/Image.c
> > > @@ -134,12 +134,14 @@ PeCoffEmuProtocolNotify (
> > >    IN  VOID            *Context
> > >    )
> > >  {
> > > -  EFI_STATUS          Status;
> > > -  UINTN               BufferSize;
> > > -  EFI_HANDLE          EmuHandle;
> > > -  EMULATOR_ENTRY      *Entry;
> > > +  EFI_STATUS                            Status;
> > > +  UINTN                                 BufferSize;
> > > +  EFI_HANDLE                            EmuHandle;
> > > +  EDKII_PECOFF_IMAGE_EMULATOR_PROTOCOL  *Emulator;
> > > +  EMULATOR_ENTRY                        *Entry;
> > >
> > >    EmuHandle = NULL;
> > > +  Emulator  = NULL;
> > >
> > >    while (TRUE) {
> > >      BufferSize = sizeof (EmuHandle);
> > > @@ -157,16 +159,19 @@ PeCoffEmuProtocolNotify (
> > >        return;
> > >      }
> > >
> > > -    Entry = AllocateZeroPool (sizeof (*Entry));
> > > -    ASSERT (Entry != NULL);
> > > -
> > >      Status = CoreHandleProtocol (
> > >                 EmuHandle,
> > >
> &gEdkiiPeCoffImageEmulatorProtocolGuid,
> > > -               (VOID **)&Entry->Emulator
> > > +               (VOID **)&Emulator
> > >                 );
> > > -    ASSERT_EFI_ERROR (Status);
> > > +    if (EFI_ERROR (Status) || Emulator == NULL) {
> > > +      continue;
> > > +    }
> > > +
> > > +    Entry = AllocateZeroPool (sizeof (*Entry));
> > > +    ASSERT (Entry != NULL);
> > >
> > > +    Entry->Emulator    = Emulator;
> > >      Entry->MachineType = Entry->Emulator-
> >MachineType;
> > >
> > >      InsertTailList (&mAvailableEmulators, &Entry-
> >Link);
> > > --
> > > 2.12.0.windows.1
> > >