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Old 11-02-2011, 12:34 AM
"Linda McLeod"
 
Default How does Fedora clean its RAM..?

How does Fedora clean its RAM..?

Does the system dump what's on unused RAM?.. Does it wait till
reboot..?
How does it work..?

How can the system be bumped-up to the next evolution of
RAM-processing..?

Is there, or can there be, a continuous wiping-cleaner that instantly
cleans RAM the moment its thht-data is dated..?

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Old 11-02-2011, 12:56 AM
Bruno Wolff III
 
Default How does Fedora clean its RAM..?

On Tue, Nov 01, 2011 at 18:34:15 -0700,
Linda McLeod <lindavaldeen@fastmail.fm> wrote:
> How does Fedora clean its RAM..?
>
> Does the system dump what's on unused RAM?.. Does it wait till
> reboot..?
> How does it work..?
>
> How can the system be bumped-up to the next evolution of
> RAM-processing..?
>
> Is there, or can there be, a continuous wiping-cleaner that instantly
> cleans RAM the moment its thht-data is dated..?

Unprivileged users don't have access to the previous contents of ram allocated
to their processes. What is the threat model you are trying to guard against?
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Old 11-02-2011, 01:31 AM
Sam Varshavchik
 
Default How does Fedora clean its RAM..?

Linda McLeod writes:


How does Fedora clean its RAM..?


Using an extra-duty cycle, with bleach, and a second rinse.


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Old 11-02-2011, 01:36 AM
g
 
Default How does Fedora clean its RAM..?

On 11/02/2011 01:34 AM, Linda McLeod wrote:
> How does Fedora clean its RAM..?

with a RAM brush. 8-D

really, what are you considering as "clean it's ram"?

as in setting ram to all zeros, or do you mean when 'ram buffer' files with
programs/data and a newly started program needs ram, and inactive/sleeping
programs/data is dumped to swap partition?

> Does the system dump what's on unused RAM?..

actually, ram is alloted. to system program areas, user program areas,
system program data, user program area.

> Does it wait till reboot..?

yes and no. again, it is a question of how you are defining "clean it's
ram".

> How does it work..?

pdg. ;-)

some programs have buffer cleaning routines, ie, keyboard input buffer,
and other such that need to start out clean. even then, as with keyboard
buffer, it does not really have to be cleaned as many well written
routines will either set a counter to show end of data storage, or what
loads buffer will put a string of zeros at end of data.

> How can the system be bumped-up to the next evolution of
> RAM-processing..?

define you understanding of "next evolution of RAM-processing"


> Is there, or can there be, a continuous wiping-cleaner that instantly
> cleans RAM the moment its thht-data is dated..?

why do you feel that it is really/always necessary?


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Old 11-02-2011, 09:26 AM
Patrick Lists
 
Default How does Fedora clean its RAM..?

On 11/02/2011 02:34 AM, Linda McLeod wrote:
> How does Fedora clean its RAM..?

On Monday morning before the start of the week it lets out the Gnomes
who then diligently start to do some serious housecleaning. There's
Spidey Gnome who climbs up the walls to get to those difficult to reach
places and do some much needed pre-winter cleaning. There's Hyper Gnome
who just runs around cleaning bits of everything it can find. Then
there's Grumpy Gnome who complains about Hyper Gnome just cleaning bits
instead of bytes. And there's Bearded Gnome who complains incessantly
about any proprietary bits it finds and makes awkward remarks about lady
Gnomes. And there's off course Lazy Gnome who just sits there pretending
to clean (the other Gnomes bought him a lmgtfy.com shirt but he didn't
get it). Finally there is Obi Wan Gnome, the Fearless Leader who tries
to keep things moving forward smoothly and always mumbles about Freedom,
Friends, Features and First.

:-)

Regards,
Patrick
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Old 11-03-2011, 01:04 AM
Joel Rees
 
Default How does Fedora clean its RAM..?

On Wed, Nov 2, 2011 at 10:56 AM, Bruno Wolff III <bruno@wolff.to> wrote:
> On Tue, Nov 01, 2011 at 18:34:15 -0700,
> *Linda McLeod <lindavaldeen@fastmail.fm> wrote:
>> How does Fedora clean its RAM..?
>>
>> Does the system dump what's on unused RAM?.. *Does it wait till
>> reboot..?
>> How does it work..?
>>
>> How can the system be bumped-up to the next evolution of
>> RAM-processing..?
>>
>> Is there, or can there be, a continuous wiping-cleaner that instantly
>> cleans RAM the moment its thht-data is dated..?
>
> Unprivileged users don't have access to the previous contents of ram allocated
> to their processes.

You're sure about that? What evidence do you offer? Can you point to
auto-scrub code paths in all the library APIs for freeing memory?

> What is the threat model you are trying to guard against?

Rather than merely imply that such threat models are beyond the scope
of Fedora, wouldn't it be better to refer the OP to a wiki article on
the subject, or to the dev list if there is no wiki article?
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Old 11-03-2011, 01:13 AM
Chris Adams
 
Default How does Fedora clean its RAM..?

Once upon a time, Joel Rees <joel.rees@gmail.com> said:
> On Wed, Nov 2, 2011 at 10:56 AM, Bruno Wolff III <bruno@wolff.to> wrote:
> > Unprivileged users don't have access to the previous contents of ram allocated
> > to their processes.
>
> You're sure about that? What evidence do you offer? Can you point to
> auto-scrub code paths in all the library APIs for freeing memory?

Read the kernel source.

> > What is the threat model you are trying to guard against?
>
> Rather than merely imply that such threat models are beyond the scope
> of Fedora, wouldn't it be better to refer the OP to a wiki article on
> the subject, or to the dev list if there is no wiki article?

Go read a book on Unix.
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Chris Adams <cmadams@hiwaay.net>
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I don't speak for anybody but myself - that's enough trouble.
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Old 11-03-2011, 01:39 AM
Joe Zeff
 
Default How does Fedora clean its RAM..?

On 11/02/2011 07:04 PM, Joel Rees wrote:
> You're sure about that? What evidence do you offer? Can you point to
> auto-scrub code paths in all the library APIs for freeing memory?

Unless the next program allocates RAM and reads from it without first
writing to it, what difference does it make? And, in the unlikely event
that some program does this, there's no way of knowing a priori what was
there before.
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Old 11-03-2011, 02:04 AM
David Quigley
 
Default How does Fedora clean its RAM..?

On 11/02/2011 22:13, Chris Adams wrote:
> Once upon a time, Joel Rees <joel.rees@gmail.com> said:
>> On Wed, Nov 2, 2011 at 10:56 AM, Bruno Wolff III <bruno@wolff.to>
>> wrote:
>> > Unprivileged users don't have access to the previous contents of
>> ram allocated
>> > to their processes.
>>
>> You're sure about that? What evidence do you offer? Can you point to
>> auto-scrub code paths in all the library APIs for freeing memory?
>
> Read the kernel source.
>
>> > What is the threat model you are trying to guard against?
>>
>> Rather than merely imply that such threat models are beyond the
>> scope
>> of Fedora, wouldn't it be better to refer the OP to a wiki article
>> on
>> the subject, or to the dev list if there is no wiki article?
>
> Go read a book on Unix.
> --
> Chris Adams <cmadams@hiwaay.net>
> Systems and Network Administrator - HiWAAY Internet Services
> I don't speak for anybody but myself - that's enough trouble.


Chris is correct in saying read the kernel source. When a page is given
to userspace by the kernel it is given zeroed out. The reason you would
need to scrub memory is if you are reallocated a page of memory by the
malloc library and not the kernel. If a memory region is freed using
free and then subsequently malloced with another call it is possible for
malloc to give you memory that hasn't been scrubbed. If malloc needs a
new set of pages to meet your request the pages it will get from the
kernel will already be zeroed.

Dave
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Old 11-03-2011, 02:38 AM
Chris Adams
 
Default How does Fedora clean its RAM..?

Once upon a time, Joe Zeff <joe@zeff.us> said:
> On 11/02/2011 07:04 PM, Joel Rees wrote:
> > You're sure about that? What evidence do you offer? Can you point to
> > auto-scrub code paths in all the library APIs for freeing memory?
>
> Unless the next program allocates RAM and reads from it without first
> writing to it, what difference does it make? And, in the unlikely event
> that some program does this, there's no way of knowing a priori what was
> there before.

That would be a security problem, since you could have information leak
from one process to another. However, Unix-like systems don't work that
way.
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I don't speak for anybody but myself - that's enough trouble.
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