linux-kernel - Re: copy_from_user / copy_to

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <200610171058.k9HAwUIo003086@laptop13.inf.utfsm.cl>
Date:	Tue, 17 Oct 2006 07:58:30 -0300
From:	"Horst H. von Brand" <vonbrand@....utfsm.cl>
To:	mfbaustx <mfbaustx@...il.com>
cc:	"Oliver Neukum" <oliver@...kum.org>, linux-kernel@...r.kernel.org
Subject: Re: copy_from_user / copy_to_user with no swap space 

mfbaustx <mfbaustx@...il.com> wrote:
> >>> No. Your code may be only partially paged into RAM.
> >>> The same can happen for any mmaped data.

> That's what I thought I read.  But then my question is:  with
> on-demand  paging, is it possible to have two processes partially
> paged?

Why shouldn't they be? The whole idea is having just /parts/ (hopefully the
ones in active use) in memory.

>         Surely, it  MUST be the case that any processes with
> overlapping logical address  spaces must be paged coherently.

I don't know what this is supposed to mean...

>                                                                So,
> while on-demand "paging-in" allows  for partial paging of a process,
> is it the case that, on a context switch,  the user-space PTE's are
> completely erased (so that you get page-faults  and can then on-demand
> page them in...)?

Each process has its own page tables, they don't get in each others
hair. And the page tables precisely manage making several processes get
access to the /same/ logical addresses, but at /different/ physical
addresses.
-- 
Dr. Horst H. von Brand                   User #22616 counter.li.org
Departamento de Informatica                    Fono: +56 32 2654431
Universidad Tecnica Federico Santa Maria             +56 32 2654239
Casilla 110-V, Valparaiso, Chile               Fax:  +56 32 2797513
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/