Re: [PATCH v1 1/6] ShellPkg: acpiview: Allow passing buffer length to DumpGasStruct()

["Krzysztof Koch" <krzysztof.koch@arm.com>]

Hi Zhichao,

Sorry about private emails, I just mistakenly hit the wrong button. I forgot that the emails do not get sent to the mailing list unless I hit 'Reply all' (silly mistake).

I see your point. I will submit v2 of this patchset with:
> DumpGasStruct (DataPtr, 4, *DbgDevInfoLen);
Replaced with
> DumpGasStruct (DataPtr, 4, GAS_LENGTH);

Is that ok?

Kind regards,

Krzysztof


-----Original Message-----
From: Gao, Zhichao <zhichao.gao@intel.com> 
Sent: Friday, July 19, 2019 9:09
To: Krzysztof Koch <Krzysztof.Koch@arm.com>
Subject: RE: [PATCH v1 1/6] ShellPkg: acpiview: Allow passing buffer length to DumpGasStruct()

HI Krzysztof,

Why do you send the email to me only? I think it is fine to send to the community. It would let more people who are interest with this component join the discuss. Maybe not . :(

Then for your comments:
Sorry,  I missed the commit message before. But I don't think keeping an inappropriate code with a commit massage to explain that is OK. If you have a plan to fix that, it should combine into one patch.
Back to the code, I don't find out the possibility of overrun of buffer when use 'GAS_LENGTH'. And DataPtr + * DbgDevInfoLen definitely overflow.
    DevInfoPtr                         DataPtr                                   EndDevInfoPtr
---|---------------------------|------------------------------|----
     |<-- DbgDevInfoLen                                                     -> |

Thanks,
Zhichao

> -----Original Message-----
> From: Krzysztof Koch [mailto:Krzysztof.Koch@arm.com]
> Sent: Friday, July 19, 2019 3:39 PM
> To: Gao, Zhichao <zhichao.gao@intel.com>
> Subject: RE: [PATCH v1 1/6] ShellPkg: acpiview: Allow passing buffer 
> length to
> DumpGasStruct()
> 
> Hi Zhichao,
> 
> Please see my comments inline marked as [Krzysztof]
> 
> Kind regards,
> 
> Krzysztof
> 
> -----Original Message-----
> From: Gao, Zhichao <zhichao.gao@intel.com>
> Sent: Friday, July 19, 2019 2:15
> To: Krzysztof Koch <Krzysztof.Koch@arm.com>; devel@edk2.groups.io
> Cc: Carsey, Jaben <jaben.carsey@intel.com>; Ni, Ray 
> <ray.ni@intel.com>; Sami Mujawar <Sami.Mujawar@arm.com>; Matteo 
> Carlini <Matteo.Carlini@arm.com>; nd <nd@arm.com>
> Subject: RE: [PATCH v1 1/6] ShellPkg: acpiview: Allow passing buffer 
> length to
> DumpGasStruct()
> 
> 
> 
> > -----Original Message-----
> > From: Krzysztof Koch [mailto:krzysztof.koch@arm.com]
> > Sent: Thursday, July 18, 2019 8:32 PM
> > To: devel@edk2.groups.io
> > Cc: Carsey, Jaben <jaben.carsey@intel.com>; Ni, Ray 
> > <ray.ni@intel.com>; Gao, Zhichao <zhichao.gao@intel.com>; 
> > Sami.Mujawar@arm.com; Matteo.Carlini@arm.com; nd@arm.com
> > Subject: [PATCH v1 1/6] ShellPkg: acpiview: Allow passing buffer 
> > length to
> > DumpGasStruct()
> >
> > Modify the signature of the DumpGasStruct() function to include the 
> > buffer length parameter and to return the number of bytes parsed by 
> > the
> function.
> >
> > This way it becomes possible to prevent buffer overruns when dumping 
> > Generic Address Structure's (GAS) fields in the acpiview table parsers.
> >
> > Update all existing DumpGasStruct() calls in acpiview to add the 
> > length argument.
> >
> > Signed-off-by: Krzysztof Koch <krzysztof.koch@arm.com>
> > ---
> >
> > Notes:
> >     v1:
> >     - Modify DumpGasStruct() signature [Krzysztof]
> >
> >  ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c              | 26
> > +++++++++++---------
> >  ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h              |  8
> > ++++--
> >
> >
> ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Dbg2/Dbg2Parser.c
> > |  2 +-
> >  3 files changed, 22 insertions(+), 14 deletions(-)
> >
> > diff --git 
> > a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
> > b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
> > index
> >
> 8b3153516d2b7d9b920ab2de0344c17798ac572c..2d6ff80e299eebe7853061d3
> > db89332197c0dc0e 100644
> > --- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
> > +++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
> > @@ -589,23 +589,27 @@ STATIC CONST ACPI_PARSER GasParser[] = {
> >
> >    @param [in] Ptr     Pointer to the start of the buffer.
> >    @param [in] Indent  Number of spaces to indent the output.
> > +  @param [in] Length  Length of the GAS structure buffer.
> > +
> > +  @retval Number of bytes parsed.
> >  **/
> > -VOID
> > +UINT32
> >  EFIAPI
> >  DumpGasStruct (
> >    IN UINT8*        Ptr,
> > -  IN UINT32        Indent
> > +  IN UINT32        Indent,
> > +  IN UINT32        Length
> >    )
> >  {
> >    Print (L"\n");
> > -  ParseAcpi (
> > -    TRUE,
> > -    Indent,
> > -    NULL,
> > -    Ptr,
> > -    GAS_LENGTH,
> > -    PARSER_PARAMS (GasParser)
> > -    );
> > +  return ParseAcpi (
> > +           TRUE,
> > +           Indent,
> > +           NULL,
> > +           Ptr,
> > +           Length,
> > +           PARSER_PARAMS (GasParser)
> > +           );
> >  }
> >
> >  /**
> > @@ -621,7 +625,7 @@ DumpGas (
> >    IN UINT8*        Ptr
> >    )
> >  {
> > -  DumpGasStruct (Ptr, 2);
> > +  DumpGasStruct (Ptr, 2, GAS_LENGTH);
> >  }
> >
> >  /**
> > diff --git 
> > a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
> > b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
> > index
> >
> 7657892d9fd2e2e14c6578611ff0cf1b6f6cd750..20ca358bddfa5953bfb1d1beba
> > ebbf3079eaba01 100644
> > --- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
> > +++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
> > @@ -405,12 +405,16 @@ ParseAcpi (
> >
> >    @param [in] Ptr     Pointer to the start of the buffer.
> >    @param [in] Indent  Number of spaces to indent the output.
> > +  @param [in] Length  Length of the GAS structure buffer.
> > +
> > +  @retval Number of bytes parsed.
> >  **/
> > -VOID
> > +UINT32
> >  EFIAPI
> >  DumpGasStruct (
> >    IN UINT8*        Ptr,
> > -  IN UINT32        Indent
> > +  IN UINT32        Indent,
> > +  IN UINT32        Length
> >    );
> >
> >  /**
> > diff --git
> >
> a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Dbg2/Dbg2Parse
> > r.c
> >
> b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Dbg2/Dbg2Parse
> > r.c
> > index
> >
> 8de5ebf74775bab8e765849cba6ef4eb6f659a5a..2c47a3f848aa2dd512c53343e
> > cf1c3c285173dd6 100644
> > ---
> >
> a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Dbg2/Dbg2Parse
> > r.c
> > +++
> >
> b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Dbg2/Dbg2Pars
> > +++ er.c
> > @@ -164,7 +164,7 @@ DumpDbgDeviceInfo (
> >    AddrSize = (UINT32*)(Ptr + (*AddrSizeOffset));
> >    while (Index < (*GasCount)) {
> >      PrintFieldName (4, L"BaseAddressRegister");
> > -    DumpGasStruct (DataPtr, 4);
> > +    DumpGasStruct (DataPtr, 4, *DbgDevInfoLen);
> 
> This input length should be GAS_LENGTH. *DbgDevInfoLen is the length 
> of the whole structure and the DataPtr is increased during the loop. 
> Inputing such a length would give the ParseAcpi function a chance to 
> overrun the DataPtr.
> 
> Thanks,
> Zhichao
> 
> [Krzysztof] You're right. This patch does not eliminate the 
> possibility for a buffer overrun when parsing the GAS structure.  This 
> patch series does not implement that yet, it's merely a refactoring 
> change in preparation for the patches which actually deal with the 
> problem. The patches which prevent buffer overruns in acpiview parsers 
> are pending on the patches which are currently in review.
> 
> In the commit message I state that the change of the DumpGasStruct() 
> function signature makes it "possible to prevent buffer overruns when 
> dumping Generic Address Structure's (GAS) fields in the acpiview table 
> parsers." The validation is coming soon.
> 
> >      PrintFieldName (4, L"Address Size");
> >      Print (L"0x%x\n", AddrSize[Index]);
> >      DataPtr += GAS_LENGTH;
> > --
> > 'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'
> >
> 
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