linux-kernel - Re: [uml-devel] [PATCH 4/5] UML - Simplify helper stack handling

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

Date:	Tue, 3 Jul 2007 08:58:30 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Blaisorblade <blaisorblade@...oo.it>
Cc:	user-mode-linux-devel@...ts.sourceforge.net,
	Jeff Dike <jdike@...toit.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [uml-devel] [PATCH 4/5] UML - Simplify helper stack handling

On Tue, 3 Jul 2007 17:28:30 +0200 Blaisorblade <blaisorblade@...oo.it> wrote:

> On giovedì 28 giugno 2007, Andrew Morton wrote:
> > So I'm running the generic version of this on i386 with 8k stacks (below),
> > with a quick LTP run.
> >
> > Holy cow, either we use a _lot_ of stack or these numbers are off:
> >
> > vmm:/home/akpm> dmesg -s 1000000|grep 'bytes left'
> > khelper used greatest stack depth: 7176 bytes left
> > khelper used greatest stack depth: 7064 bytes left
> > khelper used greatest stack depth: 6840 bytes left
> > khelper used greatest stack depth: 6812 bytes left
> > hostname used greatest stack depth: 6636 bytes left
> > uname used greatest stack depth: 6592 bytes left
> > uname used greatest stack depth: 6284 bytes left
> > hotplug used greatest stack depth: 5568 bytes left
> > rpc.nfsd used greatest stack depth: 5136 bytes left
> > chown02 used greatest stack depth: 4956 bytes left
> > fchown01 used greatest stack depth: 4892 bytes left
> 
> > That's the sum of process stack and interrupt stack, but I doubt if this
> > little box is using much interrupt stack space.
> >
> > No wonder people are still getting stack overflows with 4k stacks...
> 
> First, those numbers pretend to be _unused_ stack space.

Yep.  So fchown01 used ~3200 bytes of stack.  Problem.

> Well, UML tends to use more stack space than the rest of kernel.

That was a plain old i386 kernel.

-
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/