page_fault_in_nonpaged_area when reading existing module memory

Hi,

I've just written one of the smallest device driver ever with one driver entry and an unload function. I've compiled that for win7 X86 system. In the entry function I've chosen 2 existing modules and from both of them I wanted to read one single byte. In case of the first one no problem at all, but in the other case I've received page_fault_in_nonpaged_area! Both cases I checked the module start and end addresses in windbg several times in order to avoid this problem. I can understand that I can't write to every allocated place because that case I can destroy the whole system but read also blocked!?!?

The question is obvious: Who and why blocked my read operation? How can I get rid of that?

Regards,
Ferrit

On May 5, 4:10*am, Ferrit <ferrit....@gmail.com> wrote:
> Hi,
>
> I've just written one of the smallest device driver ever with one driver entry and an unload function. I've compiled that for win7 X86 system. In the entry function I've chosen 2 existing modules and from both of them I wanted to read one single byte. In case of the first one no problem at all, but in the other case I've received page_fault_in_nonpaged_area! Both cases Ichecked the module start and end addresses in windbg several times in order to avoid this problem. I can understand that I can't write to every allocated place because that case I can destroy the whole system but read also blocked!?!?
>
> The question is obvious: Who and why blocked my read operation? How can Iget rid of that?
>
> Regards,
> Ferrit

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