Re: [PATCH 3/7] x86, kaslr: find minimum safe relocation position

[Kees Cook]

On Thu, Oct 3, 2013 at 3:23 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> On 10/03/2013 01:53 PM, Kees Cook wrote:
>> Examine all the known unsafe areas and avoid them by just raising the
>> minimum relocation position to be past them.
>>
>> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
>
>> +     /* Minimum location must be above all these regions: */
>
> This is highly problematic.  The standard protocol is to hoist the
> initramfs as high as possible in memory, so this may really unacceptably
> restrict the available range.

Doesn't this depend on the boot loader's behavior?

> It would be better to treat these the same as reserved regions in the
> e820 map as far as the address space picking algorithm is concerned.

Could this be considered a future optimization, or do you feel this is
required even for this first patch series landing?

-Kees

-- 
Kees Cook
Chrome OS Security
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