Re: [PATCH v2 1/1] MdePkg: Refine casting expression result to bigger size

["Wu, Hao A" <hao.a.wu@intel.com>]

> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Tuesday, January 24, 2017 5:54 PM
> To: Wu, Hao A
> Cc: edk2-devel@ml01.01.org
> Subject: Re: [edk2] [PATCH v2 1/1] MdePkg: Refine casting expression result to
> bigger size
> 
> On 01/24/17 08:25, Hao Wu wrote:
> > There are cases that the operands of an expression are all with rank less
> > than UINT64/INT64 and the result of the expression is explicitly casted to
> > UINT64/INT64 to fit the target size.
> >
> > An example will be:
> > UINT32 a,b;
> > // a and b can be any unsigned int type with rank less than UINT64, like
> > // UINT8, UINT16, etc.
> > UINT64 c;
> > c = (UINT64) (a + b);
> >
> > Some static code checkers may warn that the expression result might
> > overflow within the rank of "int" (integer promotions) and the result is
> > then cast to a bigger size.
> >
> > The commit refines codes by the following rules:
> > 1). When the expression will not overflow within the rank of "int", remove
> > the explicit type casts:
> > c = a + b;
> >
> > 2). When the expression is possible to overflow the range of unsigned int/
> > int:
> > c = (UINT64)a + b;
> >
> > Contributed-under: TianoCore Contribution Agreement 1.0
> > Signed-off-by: Hao Wu <hao.a.wu@intel.com>
> > ---
> >  MdePkg/Library/BaseLib/String.c                              |  4 ++--
> >  MdePkg/Library/BasePeCoffLib/BasePeCoff.c                    | 12 +++++-------
> >  MdePkg/Library/BaseS3PciLib/S3PciLib.c                       |  4 ++--
> >  MdePkg/Library/SmmMemoryAllocationLib/MemoryAllocationLib.c  |  4 ++--
> >  MdePkg/Library/UefiMemoryAllocationLib/MemoryAllocationLib.c |  4 ++--
> >  5 files changed, 13 insertions(+), 15 deletions(-)
> >
> > diff --git a/MdePkg/Library/BaseLib/String.c
> b/MdePkg/Library/BaseLib/String.c
> > index e84bf50..4151e0e 100644
> > --- a/MdePkg/Library/BaseLib/String.c
> > +++ b/MdePkg/Library/BaseLib/String.c
> > @@ -586,7 +586,7 @@ InternalHexCharToUintn (
> >      return Char - L'0';
> >    }
> >
> > -  return (UINTN) (10 + InternalCharToUpper (Char) - L'A');
> > +  return (10 + InternalCharToUpper (Char) - L'A');
> >  }
> >
> >  /**
> > @@ -1211,7 +1211,7 @@ InternalAsciiHexCharToUintn (
> >      return Char - '0';
> >    }
> >
> > -  return (UINTN) (10 + InternalBaseLibAsciiToUpper (Char) - 'A');
> > +  return (10 + InternalBaseLibAsciiToUpper (Char) - 'A');
> >  }
> >
> >
> > diff --git a/MdePkg/Library/BasePeCoffLib/BasePeCoff.c
> b/MdePkg/Library/BasePeCoffLib/BasePeCoff.c
> > index 33cad23..8d1daba 100644
> > --- a/MdePkg/Library/BasePeCoffLib/BasePeCoff.c
> > +++ b/MdePkg/Library/BasePeCoffLib/BasePeCoff.c
> > @@ -15,7 +15,7 @@
> >    PeCoffLoaderGetPeHeader() routine will do basic check for PE/COFF header.
> >    PeCoffLoaderGetImageInfo() routine will do basic check for whole PE/COFF
> image.
> >
> > -  Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR>
> > +  Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
> >    Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
> >    This program and the accompanying materials
> >    are licensed and made available under the terms and conditions of the BSD
> License
> > @@ -703,12 +703,10 @@ PeCoffLoaderGetImageInfo (
> >        //
> >        DebugDirectoryEntryFileOffset = 0;
> >
> > -      SectionHeaderOffset = (UINTN)(
> > -                               ImageContext->PeCoffHeaderOffset +
> > -                               sizeof (UINT32) +
> > -                               sizeof (EFI_IMAGE_FILE_HEADER) +
> > -                               Hdr.Pe32->FileHeader.SizeOfOptionalHeader
> > -                               );
> > +      SectionHeaderOffset = ImageContext->PeCoffHeaderOffset +
> > +                            sizeof (UINT32) +
> > +                            sizeof (EFI_IMAGE_FILE_HEADER) +
> > +                            Hdr.Pe32->FileHeader.SizeOfOptionalHeader;
> >
> >        for (Index = 0; Index < Hdr.Pe32->FileHeader.NumberOfSections; Index++)
> {
> >          //
> > diff --git a/MdePkg/Library/BaseS3PciLib/S3PciLib.c
> b/MdePkg/Library/BaseS3PciLib/S3PciLib.c
> > index e29f7fe..27342b0 100644
> > --- a/MdePkg/Library/BaseS3PciLib/S3PciLib.c
> > +++ b/MdePkg/Library/BaseS3PciLib/S3PciLib.c
> > @@ -3,7 +3,7 @@
> >    the PCI operations to be replayed during an S3 resume. This library class
> >    maps directly on top of the PciLib class.
> >
> > -  Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
> > +  Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
> >
> >    This program and the accompanying materials
> >    are licensed and made available under the terms and conditions
> > @@ -25,7 +25,7 @@
> >  #include <Library/S3PciLib.h>
> >
> >  #define PCILIB_TO_COMMON_ADDRESS(Address) \
> > -        ((UINT64) ((((UINTN) ((Address>>20) & 0xff)) << 24) + (((UINTN)
> ((Address>>15) & 0x1f)) << 16) + (((UINTN) ((Address>>12) & 0x07)) << 8) +
> ((UINTN) (Address & 0xfff ))))
> > +        ((((UINTN) ((Address>>20) & 0xff)) << 24) + (((UINTN) ((Address>>15) &
> 0x1f)) << 16) + (((UINTN) ((Address>>12) & 0x07)) << 8) + ((UINTN) (Address &
> 0xfff )))
> >
> >  /**
> >    Saves a PCI configuration value to the boot script.
> 
> I think this change is potentially unsafe, without auditing all uses of
> PCILIB_TO_COMMON_ADDRESS(). In a 32-bit build, the type of the result
> will no longer be UINT64 but UINT32, and that can cause problems in
> several contexts. For example:
> 
> - as an operand to the sizeof operator
> - when it's being relied upon to cause conversion to UINT64, for example
> another (UINT32) operand could be added to it
> - when it is passed through a variable argument list
> 
> It might be safe, but there's no way to tell without auditing all the
> call sites. So let me see...
> 
> Apparently this macro is only passed to S3BootScriptSavePciCfgWrite() as
> second argument, within the same file, and that argument is covered by
> the function prototype explicitly, with type UINT64. So the change
> should be safe.
> 

Thanks for the checking. I did search the whole edk2 repository for the
reference of "PCILIB_TO_COMMON_ADDRESS" and it is only comsumed by the
function you mentioned.

> (I see the same macro definition and kind of invocation in
> "QuarkPlatformPkg/Acpi/DxeSmm/AcpiSmm/AcpiSmmPlatform.c"; I didn't try
> to audit that file.)
> 
> The rest looks okay too.
> 
> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
> 

Many thanks for the feedbacks and the effort for reviewing the patch.

> (If you go ahead and submit a 30-part series that does this kind of
> fixup all over the tree, please don't expect me to review it all -- I'm
> okay reviewing OvmfPkg and ArmVirtPkg changes, but I can't take on the
> rest. This kind of patch cannot be reviewed without consulting a really
> wide context.)
> 

I am thinking if the package level patch contains too many changes, I
might break it into multiple module-level patches and include module
owners/experts to help reviewing them.

Best Regards,
Hao Wu

> Thanks
> Laszlo
> 
> 
> > diff --git
> a/MdePkg/Library/SmmMemoryAllocationLib/MemoryAllocationLib.c
> b/MdePkg/Library/SmmMemoryAllocationLib/MemoryAllocationLib.c
> > index 937165a..592cced 100644
> > --- a/MdePkg/Library/SmmMemoryAllocationLib/MemoryAllocationLib.c
> > +++ b/MdePkg/Library/SmmMemoryAllocationLib/MemoryAllocationLib.c
> > @@ -12,7 +12,7 @@
> >    allocation for the Reserved memory types are not supported and will
> always
> >    return NULL.
> >
> > -  Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
> > +  Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
> >    This program and the accompanying materials
> >    are licensed and made available under the terms and conditions of the BSD
> License
> >    which accompanies this distribution.  The full text of the license may be
> found at
> > @@ -343,7 +343,7 @@ InternalAllocateAlignedPages (
> >        Status = gSmst->SmmFreePages (Memory, UnalignedPages);
> >        ASSERT_EFI_ERROR (Status);
> >      }
> > -    Memory         = (EFI_PHYSICAL_ADDRESS) (AlignedMemory +
> EFI_PAGES_TO_SIZE (Pages));
> > +    Memory         = AlignedMemory + EFI_PAGES_TO_SIZE (Pages);
> >      UnalignedPages = RealPages - Pages - UnalignedPages;
> >      if (UnalignedPages > 0) {
> >        //
> > diff --git a/MdePkg/Library/UefiMemoryAllocationLib/MemoryAllocationLib.c
> b/MdePkg/Library/UefiMemoryAllocationLib/MemoryAllocationLib.c
> > index 3da5e211..3bd3aef 100644
> > --- a/MdePkg/Library/UefiMemoryAllocationLib/MemoryAllocationLib.c
> > +++ b/MdePkg/Library/UefiMemoryAllocationLib/MemoryAllocationLib.c
> > @@ -2,7 +2,7 @@
> >    Support routines for memory allocation routines based
> >    on boot services for Dxe phase drivers.
> >
> > -  Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
> > +  Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
> >    This program and the accompanying materials
> >    are licensed and made available under the terms and conditions of the BSD
> License
> >    which accompanies this distribution.  The full text of the license may be
> found at
> > @@ -216,7 +216,7 @@ InternalAllocateAlignedPages (
> >        Status = gBS->FreePages (Memory, UnalignedPages);
> >        ASSERT_EFI_ERROR (Status);
> >      }
> > -    Memory         = (EFI_PHYSICAL_ADDRESS) (AlignedMemory +
> EFI_PAGES_TO_SIZE (Pages));
> > +    Memory         = AlignedMemory + EFI_PAGES_TO_SIZE (Pages);
> >      UnalignedPages = RealPages - Pages - UnalignedPages;
> >      if (UnalignedPages > 0) {
> >        //
> >