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

["Gao, Zhichao" <zhichao.gao@intel.com>]

> -----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

>      PrintFieldName (4, L"Address Size");
>      Print (L"0x%x\n", AddrSize[Index]);
>      DataPtr += GAS_LENGTH;
> --
> 'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'
>