linux-kernel - Re: [PATCH v2] x86, kaslr: propagate base load address calculation

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Message-ID: <CAGXu5jKQDfhvr04OAxeFO+nhpnVgQ40444SvBPpCZkF4CVa28g@mail.gmail.com>
Date:	Tue, 17 Feb 2015 19:33:40 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Jiri Kosina <jkosina@...e.cz>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	LKML <linux-kernel@...r.kernel.org>,
	live-patching@...r.kernel.org, Linux-MM <linux-mm@...ck.org>,
	"x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH v2] x86, kaslr: propagate base load address calculation

On Tue, Feb 17, 2015 at 2:31 PM, Borislav Petkov <bp@...en8.de> wrote:
> On Tue, Feb 17, 2015 at 08:45:53AM -0800, Kees Cook wrote:
>> Maybe it should say:
>>
>> Kernel offset: disabled
>>
>> for maximum clarity?
>
> I.e.:
>
> ---
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 78c91bbf50e2..16b6043cb073 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -843,10 +843,14 @@ static void __init trim_low_memory_range(void)
>  static int
>  dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
>  {
> -       pr_emerg("Kernel Offset: 0x%lx from 0x%lx "
> -                "(relocation range: 0x%lx-0x%lx)\n",
> -                (unsigned long)&_text - __START_KERNEL, __START_KERNEL,
> -                __START_KERNEL_map, MODULES_VADDR-1);
> +       if (kaslr_enabled)
> +               pr_emerg("Kernel Offset: 0x%lx from 0x%lx (relocation range: 0x%lx-0x%lx)\n",
> +                        (unsigned long)&_text - __START_KERNEL,
> +                        __START_KERNEL,
> +                        __START_KERNEL_map,
> +                        MODULES_VADDR-1);
> +       else
> +               pr_emerg("Kernel Offset: disabled\n");
>
>         return 0;
>  }
> ---
>
> ?

You are the best. :)

Acked-by: Kees Cook <keescook@...omium.org>

-Kees

>
> --
> Regards/Gruss,
>     Boris.
>
> ECO tip #101: Trim your mails when you reply.
> --



-- 
Kees Cook
Chrome OS Security
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