linux-kernel - Re: [PATCH] FDPIC: Ignore the loader's PT_GNU

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 for Android: free password hash cracker in your pocket

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

Date:	Thu, 9 Jul 2009 12:19:30 +0200
From:	Pavel Machek <pavel@....cz>
To:	Mike Frysinger <vapier.adi@...il.com>
Cc:	David Howells <dhowells@...hat.com>, rgetz@...ckfin.uclinux.org,
	lethal@...ux-sh.org, gerg@...inux.org,
	uclinux-dist-devel@...ckfin.uclinux.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] FDPIC: Ignore the loader's PT_GNU_STACK when
	calculating the stack size

On Wed 2009-07-08 14:48:51, Mike Frysinger wrote:
> On Fri, Jul 3, 2009 at 23:34, Pavel Machek wrote:
> > On Wed 2009-07-08 12:01:40, David Howells wrote:
> >> Pavel Machek <pavel@....cz> wrote:
> >>
> >> > The patch seems wrong to me; loader needs the stack, too, right?
> >> >
> >> > What about making sure that the loader specifies reasonable stack
> >> > size, instead?
> >>
> >> The loader doesn't need its own stack, unless it _is_ the executable.  It uses
> >> the executable's stack.  The problem is that the executable and the loader can
> >> both specify the stack size for NOMMU, but which one do we pick, or do we
> >> consider both.
> >
> > Imageine loader needs 64K, while executable only needs 4K. You surely
> > want to execute it with 64K stack, because it will not fit into 4K?
> 
> i really dont think this is realistic.  there is exactly one ldso that
> everyone uses under FDPIC ELF, and it needs a very minuscule stack.

Not very realistic; but that argues that the patch is NOP.

And if it _is_ realistic, the patch adds a bug.

=> patch is bad idea.
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
--
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/