problem mapping physical address from /dev/mem

[rohan puri]

On Fri, Oct 7, 2011 at 4:13 AM, Vaibhav Jain <vjoss197 at gmail.com> wrote:

>
>
> On Thu, Oct 6, 2011 at 11:28 AM, Mulyadi Santosa <
> mulyadi.santosa at gmail.com> wrote:
>
>> Hi...
>>
>> On Thu, Oct 6, 2011 at 02:34, Vaibhav Jain <vjoss197 at gmail.com> wrote:
>> > Hi,
>> >
>> > I am trying to run a program that scans memory from a given physical
>> address
>> > using /dev/mem.
>> > It uses mmap to map physical address from /dev/mem. So to start with I
>> used
>> > /proc/iomem to look up the
>> > physical memory mapping and found the address 00010000 to be the
>> starting
>> > address for System ram. But whenever I
>> > provide this address to the program it throws an error of "Operation not
>> > permitted".
>>
>> Probably this could also due to mmap NULL dereferencing protection (at
>> least that's how I name it :) )
>>
>> By default, the lowest 65536 byte (10000 in hex) is protected from
>> mapping etc. It practically render such null dererefencing useless.
>>
>>
>> --
>> regards,
>>
>> Mulyadi Santosa
>> Freelance Linux trainer and consultant
>>
>> blog: the-hydra.blogspot.com
>> training: mulyaditraining.blogspot.com
>>
>
> Hi,
>
> I tried the same with other addresses (greater than 0x10000 ) also but it
> is throwing the same error.
> Is there a way to get over this ?
>
> Thanks
> Vaibhav Jain
>
>
>
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>
> Hi Vaibhav,

This is how it can be done. Refer link
http://www.theknotter.net/system-memory-dumps-on-linux/

I have attached the modified code which disables the socket creation part
and dumps the output in a file.

Regards,
Rohan Puri
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