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

Kees Cook
2015-02-18T03:33:43Z

On Tue, Feb 17, 2015 at 2:31 PM, Borislav Petkov <bp@alien8.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@chromium.org>

-Kees

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

--
Kees Cook
Chrome OS Security