[ros-dev] Undocumented field in PEB?

[Alex Ionescu]

There is nothing "undocumented". LARGE_INTEGER is 8 bytes long and  
alignment padding is 8 bytes on x86.

On 6-Mar-09, at 2:46 AM, Jun Koi wrote:

> Hi,
>
> I notice that in Windows Vista - and also Windows XP - there seems to
> be an undocumented field in PEB.
>
>> From Windbg, I found some below fields in PEB structure'
>
> ...
> +0x064 NumberOfProcessors : Uint4B
> +0x068 NtGlobalFlag     : Uint4B
> +0x070 CriticalSectionTimeout : _LARGE_INTEGER
> ...
>
> We can see that NtGlobalFlag is at offset 0x68, and is 4 bytes field.
> So the next field should be at 0x6C. However, CriticalSectionTimeout
> is at 0x70.
>
> - So the question is why that happens? I suspect that there is an
> undocumented field after NtGlobalFlag, which is removed from the
> debugging data. Any idea?
>
> - Another thing: ReactOS now faithfully declares the PEB structure
> like above, without that secret 4 bytes hole. As a result, the
> ReactOS's PEB size is 4 bytes short than PEB structure in Windows. Do
> we need to care about that? Or not?
>
> Thanks,
> J
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Best regards,
Alex Ionescu