linux-kernel - Re: [PATCH 2/2] UML - Fix kernel stack size on x86

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] [day] [month] [year] [list]

Date:	Wed, 6 Jun 2007 11:03:14 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Jeff Dike <jdike@...toit.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	uml-devel <user-mode-linux-devel@...ts.sourceforge.net>
Subject: Re: [PATCH 2/2] UML - Fix kernel stack size on x86_64

On Wed, 6 Jun 2007 11:11:34 -0400 Jeff Dike <jdike@...toit.com> wrote:

> On Tue, Jun 05, 2007 at 06:20:24PM -0700, Andrew Morton wrote:
> > If you do
> > 
> > -	int "Kernel stack size order"
> > +	int
> > 
> > then this rule will no longer be offered to the user and `make oldconfig'
> > (actually anythingconfig) will override whatever happens to be in .config
> > for KERNEL_STACK_ORDER.
> 
> You're saying that making an option user-visible changes whether
> *config overrides .config?  That's non-intuitive.

Yeah, I thought so.  I discovered it by comparing the behaviour of your
patch against the behaviour of CONFIG_BASE_SMALL, fiddling around and
then saying "wtf".

> > I'm not sure if that's actually what you want, but if the current situation
> > is that a random CONFIG_KERNEL_STACK_ORDER=0 left over in .config will
> > break the kernel at runtime then I think something sterner than editing
> > defconfig is needed?
> 
> That's a good point, but I think I do want it user-visible.  If
> someone sees someething I suspect to be a stack overflow, I'd like to
> be able to tell them to bump KERNEL_STACK_ORDER and see if the problem
> goes away.
> 
> As for something sterner, it turns out that Kbuild provides some
> support for this.  So, drop the previous patch in favor of this one:
> 
> Force KERNEL_STACK_ORDER to be at least 1 on UML/x86_64.
> 
> Signed-off-by: Jeff Dike <jdike@...ux.intel.com>
> --
>  arch/um/Kconfig |    1 +
>  1 file changed, 1 insertion(+)
> 
> Index: linux-2.6.21-mm/arch/um/Kconfig
> ===================================================================
> --- linux-2.6.21-mm.orig/arch/um/Kconfig	2007-06-06 09:28:13.000000000 -0400
> +++ linux-2.6.21-mm/arch/um/Kconfig	2007-06-06 11:08:49.000000000 -0400
> @@ -278,6 +278,7 @@ config HIGHMEM
>  config KERNEL_STACK_ORDER
>  	int "Kernel stack size order"
>  	default 1 if 64BIT
> +	range 1 10 if 64BIT
>  	default 0 if !64BIT
>  	help
>  	This option determines the size of UML kernel stacks.  They will

heh, fair enough.
-
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/