From: Rusty Russell <rusty@rustcorp.com.au>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>,
Siarhei Liakh <sliakh.lkml@gmail.com>,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
James Morris <jmorris@namei.org>,
Andrew Morton <akpm@linux-foundation.org>, Andi Kleen <ak@muc.de>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-cris-kernel@axis.com
Subject: Re: [PATCH v5] RO/NX protection for loadable kernel modules
Date: Sun, 12 Jul 2009 14:10:39 +0930 [thread overview]
Message-ID: <200907121410.39874.rusty@rustcorp.com.au> (raw)
In-Reply-To: <20090711084958.69ff9196@infradead.org>
On Sun, 12 Jul 2009 01:19:58 am Arjan van de Ven wrote:
> Rusty Russell <rusty@rustcorp.com.au> wrote:
> > I have a question about this patch though: I think it's unsafe in
> > general to mark the last partial page as NX (we asked for executable
> > pages, this could remove executable from some unrelated allocation).
>
> we vmalloc / g_f_p modules right? so we don't share the last page.
Historically yes, but I don't think we should be counting on it. It makes
sense to kmalloc for small modules, and it's arch specific code.
OTOH, a quick grep shows currently only cris does kmalloc, and that's a config
option.
It might be time to unify this code. If we rename MODULE_START to
MODULE_VADDR on MIPS, then ignoring CRIS there's only two real variants;
vmalloc and __vmalloc.
(I like the idea of trying kmalloc and falling back, simply because it reduces
TLB pressure, but that's probably best done after unification).
Thoughts?
Rusty.
next prev parent reply other threads:[~2009-07-12 4:40 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-08 23:10 [PATCH v5] RO/NX protection for loadable kernel modules Siarhei Liakh
[not found] ` <20090710112403.GC3760@elte.hu>
[not found] ` <200907111537.03191.rusty@rustcorp.com.au>
2009-07-11 7:30 ` Ingo Molnar
2009-07-11 11:22 ` Rusty Russell
2009-07-11 8:51 ` Rusty Russell
2009-07-11 15:49 ` Arjan van de Ven
2009-07-12 4:40 ` Rusty Russell [this message]
2009-07-12 4:45 ` H. Peter Anvin
2009-07-12 7:45 ` Arjan van de Ven
2009-07-12 9:25 ` Andi Kleen
2009-07-12 9:58 ` Rusty Russell
2009-07-12 15:32 ` Arjan van de Ven
2009-07-12 17:33 ` Greg KH
2009-07-12 21:58 ` Arjan van de Ven
2009-07-12 22:14 ` Greg KH
2009-07-13 9:02 ` Andi Kleen
2009-07-12 23:21 ` Rusty Russell
2009-07-13 3:11 ` Arjan van de Ven
2009-07-12 9:24 ` Andi Kleen
2009-07-13 16:59 ` Roland Dreier
2009-07-13 10:59 ` Jesper Nilsson
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