Does Linux process exist information leakage?

[夏业添]

Hi,

Could you explain more about how the OS initialize the malloced pages? Or
which part of the kernel code can do thatThanks!

2012/1/12 Dave Hylands <dhylands at gmail.com>

> Hi,
>
> On Wed, Jan 11, 2012 at 4:53 AM, 夏业添 <summerxyt at gmail.com> wrote:
> > Hi,
> >    My tutor asked me to test whether one process leaves information in
> > memory after it is dead. I tried to search some article about such thing
> on
> > the Internet but there seems to be no one discuss about it. And after
> that,
> > I tried to write some program in the User Mode to test it, using fork()
> to
> > create lots of processes and filling char 'a' into a 102400 bytes char
> array
> > in each process. Then I used malloc() to get some memory to seek char
> 'a' in
> > a new one process or many new processes, but failed. All memory I
> malloced
> > was full of zero.
>
> Yeah - so if it were possible for one process to get information about
> another process like that you would have a security leak.
>
> >    As the man page of malloc said:"The memory is not initialized", I
> believe
> > that the memory which was got by malloc() could be used by other process,
> > and therefor information leakage exists. But how can I test it? Or where
> can
> > I get related information?
>
> All pages allocated from the OS will be initially zero'd, however,
> once your process owns the page, if you filled it with Z's and then
> freed it and reallocated you might very weill get your Z's back
> instead of 0's. You'll never get data from another process though.
>
> --
> Dave Hylands
> Shuswap, BC, Canada
> http://www.davehylands.com
>
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