Re: [PATCH 01/30] x86, mm: do not set _PAGE_USER for init_mm page tables

[Borislav Petkov]

On Wed, Nov 08, 2017 at 11:46:47AM -0800, Dave Hansen wrote:
> 
> From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> 
> init_mm is for kernel-exclusive use.  If someone is allocating page
> tables for it, do not set _PAGE_USER on them.
> 
> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Moritz Lipp <moritz.lipp@xxxxxxxxxxxxxx>
> Cc: Daniel Gruss <daniel.gruss@xxxxxxxxxxxxxx>
> Cc: Michael Schwarz <michael.schwarz@xxxxxxxxxxxxxx>
> Cc: Richard Fellner <richard.fellner@xxxxxxxxxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: x86@xxxxxxxxxx
> ---
> 
>  b/arch/x86/include/asm/pgalloc.h |   33 ++++++++++++++++++++++++++++-----
>  1 file changed, 28 insertions(+), 5 deletions(-)
> 
> diff -puN arch/x86/include/asm/pgalloc.h~kaiser-prep-clear-_PAGE_USER-for-init_mm arch/x86/include/asm/pgalloc.h
> --- a/arch/x86/include/asm/pgalloc.h~kaiser-prep-clear-_PAGE_USER-for-init_mm	2017-11-08 10:45:25.928681403 -0800
> +++ b/arch/x86/include/asm/pgalloc.h	2017-11-08 10:45:25.931681403 -0800
> @@ -61,20 +61,37 @@ static inline void __pte_free_tlb(struct
>  	___pte_free_tlb(tlb, pte);
>  }
>  
> +/*
> + * init_mm is for kernel-exclusive use.  Any page tables that
> + * are seteup for it should not be usable by userspace.

s/seteup/setup/

-- 
Regards/Gruss,
    Boris.

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