linux-kernel - Re: [PATCH 3/3 V13] RO/NX protection for loadable kernel

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Date:	Wed, 22 Dec 2010 16:35:19 -0500
From:	Valdis.Kletnieks@...edu
To:	Ingo Molnar <mingo@...e.hu>
Cc:	mat <castet.matthieu@...e.fr>, Kees Cook <kees.cook@...onical.com>,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, linux-next@...r.kernel.org,
	Arjan van de Ven <arjan@...radead.org>,
	James Morris <jmorris@...ei.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <ak@....de>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Dave Jones <davej@...hat.com>,
	Siarhei Liakh <sliakh.lkml@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH 3/3 V13] RO/NX protection for loadable kernel

On Wed, 22 Dec 2010 13:40:19 +0100, Ingo Molnar said:
> 
> * mat <castet.matthieu@...e.fr> wrote:
> 
> > Le Wed, 8 Dec 2010 14:19:51 -0800,
> > Kees Cook <kees.cook@...onical.com> a écrit :
> > 
> > > On Fri, Nov 26, 2010 at 06:23:55PM +0100, mat wrote:
> > > > could you try the attached patch ?
> > > > 
> > > > on module load, we sort the __jump_table section. So we should make
> > > > it writable.
> > > > 
> > > > 
> > > > Matthieu
> > > 
> > > > diff --git a/arch/x86/include/asm/jump_label.h
> > > > b/arch/x86/include/asm/jump_label.h index f52d42e..574dbc2 100644
> > > > --- a/arch/x86/include/asm/jump_label.h
> > > > +++ b/arch/x86/include/asm/jump_label.h
> > > > @@ -14,7 +14,7 @@
> > > >  	do
> > > > {							\ asm
> > > > goto("1:"					\
> > > > JUMP_LABEL_INITIAL_NOP			\
> > > > -			".pushsection __jump_table,  \"a\" \n\t"\
> > > > +			".pushsection __jump_table,  \"aw\" \n\t"\
> > > >  			_ASM_PTR "1b, %l[" #label "], %c0 \n\t" \
> > > >  			".popsection \n\t"			\
> > > >  			: :  "i" (key) :  : label);
> > > > \
> > > 
> > > Acked-by: Kees Cook <kees.cook@...onical.com>
> > > 
> > > Can this please get committed to tip?
> > I think it is not need anymore with  Steven Rostedt patch [1]
> > 
> > Matthieu
> > 
> > [1]
> > > > Here we set the text read only before we call the notifiers. The
> > > > function tracer changes the calls to mcount into nops via a notifier
> > > > call so this must be done after the module notifiers.
> 
> What's the status of this bug?
> 
> If we still need the patch then please submit it standalone with a proper subject 
> line, with acks/signoffs added, etc.

Steve Rostedt's patch that moves the setting of the page permissions seems to
make this patch no longer necessary.  I tripped over this same issue, but the
version in the latest -mmotm does not need it, as it includes Steve's fix.

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