Messages in this thread | | | Date | Mon, 13 Jul 2009 12:59:49 +0200 | From | Jesper Nilsson <> | Subject | Re: [PATCH v5] RO/NX protection for loadable kernel modules |
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On Sun, Jul 12, 2009 at 06:40:39AM +0200, Rusty Russell wrote: > 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.
...which is a not often used debug 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.
/^JN - Jesper Nilsson -- Jesper Nilsson -- jesper.nilsson@axis.com
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