cat: /dev/mem: Operation not permitted

[Tony Arnold]

Dotan,

Dotan Cohen wrote:

>> I then tried sudo cat /dev/mem > mem.txt. It sat there for a while, and
>> I got the same error as you when I hit ctrl-C. mem.txt did contain some
>> data.
>>
> 
> I didn't even hit Ctrl-C. It just gave me the error.

It's weird because sudo cat /dev/mem > mem.txt results in about 1MB of
data in mem.txt. So some of /dev/mem is readable.

I also get the following from dmesg:

Program cat tried to access /dev/mem between 101000->102000.

> On any other Linux-based OS this is possible, in fact, it is good for
> recovering lost files.

It's either some kernel limitation/protection or a bug!

Regards,
Tony.
-- 
Tony Arnold,                        Tel: +44 (0) 161 275 6093
Head of IT Security,                Fax: +44 (0) 870 136 1004
University of Manchester,           Mob: +44 (0) 773 330 0039
Manchester M13 9PL.                 Email: tony.arnold at manchester.ac.uk