[uml-devel] [PATCH] uml: fix pte_mkread setting page read/write

[uml-devel] [PATCH] uml: fix pte_mkread setting page read/write

[Paolo 'Blaisorblade' Giarrusso]

Fix the fact that pte_mkread set _PAGE_RW instead of _PAGE_USER (the logic is
copied from i386 in most place, so it is really as bad as you're thinking).

Thus currently page tables are more permissive than they should.

Such a change may trigger other latent bugs, so be careful with this.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Index: linux-2.6.git/include/asm-um/pgtable.h
===================================================================
--- linux-2.6.git.orig/include/asm-um/pgtable.h
+++ linux-2.6.git/include/asm-um/pgtable.h
@@ -270,7 +270,7 @@ static inline pte_t pte_wrprotect(pte_t 
 
 static inline pte_t pte_mkread(pte_t pte)
 { 
-	pte_set_bits(pte, _PAGE_RW);
+	pte_set_bits(pte, _PAGE_USER);
 	return(pte_mknewprot(pte)); 
 }
 

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Re: [uml-devel] [PATCH] uml: fix pte_mkread setting page read/write

[Blaisorblade]

On Saturday 10 February 2007 18:27, Paolo 'Blaisorblade' Giarrusso wrote:
> Fix the fact that pte_mkread set _PAGE_RW instead of _PAGE_USER (the logic
> is copied from i386 in most place, so it is really as bad as you're
> thinking).
>
> Thus currently page tables are more permissive than they should.
>
> Such a change may trigger other latent bugs, so be careful with this.
>
> Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Jeff, no answer to this yet? I've just checked and it's not on the patchset 
page either.
-- 
Inform me of my mistakes, so I can add them to my list!
Paolo Giarrusso, aka Blaisorblade
http://www.user-mode-linux.org/~blaisorblade
Chiacchiera con i tuoi amici in tempo reale! 
 http://it.yahoo.com/mail_it/foot/*http://it.messenger.yahoo.com 


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Re: [uml-devel] [PATCH] uml: fix pte_mkread setting page read/write

[Jeff Dike]

On Mon, Feb 19, 2007 at 06:34:42PM +0100, Blaisorblade wrote:
> Jeff, no answer to this yet? I've just checked and it's not on the patchset 
> page either.

I already had it in my -mm patchset, minus any attribution, so I guess
I cooked it up myself.  I've been running with it for a long time, so it's
fine by me.

I tossed in your description and SOB and I'll get it off to Andrew unless
you want to send it in first.

				Jeff

-- 
Work email - jdike at linux dot intel dot com

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Re: [uml-devel] [PATCH] uml: fix pte_mkread setting page read/write

[Blaisorblade]

On Monday 19 February 2007 20:52, Jeff Dike wrote:
> On Mon, Feb 19, 2007 at 06:34:42PM +0100, Blaisorblade wrote:
> > Jeff, no answer to this yet? I've just checked and it's not on the
> > patchset page either.

> I already had it in my -mm patchset, minus any attribution, so I guess
> I cooked it up myself.

Possibly - or I already sent it time ago (I've had it for long time).

> I've been running with it for a long time, so it's 
> fine by me.
>
> I tossed in your description and SOB and I'll get it off to Andrew unless
> you want to send it in first.

You can send it to Andrew - since I have less time than in the past, to avoid 
delaying patches until they're perfect I'm going to send more patches through 
your tree. With this patch, I also wanted to test the process, and see if it 
can work for you.
-- 
Inform me of my mistakes, so I can add them to my list!
Paolo Giarrusso, aka Blaisorblade
http://www.user-mode-linux.org/~blaisorblade
Chiacchiera con i tuoi amici in tempo reale! 
 http://it.yahoo.com/mail_it/foot/*http://it.messenger.yahoo.com 


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