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Date: Tue, 9 Apr 2013 11:46:08 -0700
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Subject: Re: [kernel-hardening] Re: [PATCH] x86: make IDT read-only
From: Kees Cook <keescook@chromium.org>
To: "H. Peter Anvin" <hpa@zytor.com>
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On Tue, Apr 9, 2013 at 11:39 AM, H. Peter Anvin <hpa@zytor.com> wrote:
> On 04/09/2013 11:31 AM, Kees Cook wrote:
>>>> ...
>>>> 0xffff880001e00000-0xffff88001fe00000         480M     RW         PSE GLB NX pmd
>>>>
>>>
>>> That is the 1:1 memory map area...
>>
>> Meaning what?
>>
>> -Kees
>>
>
> That's the area in which we just map 1:1 to memory.  Anything allocated
> with e.g. kmalloc() ends up with those addresses.

Ah-ha! Yes, I see now when comparing the debug/kernel_page_tables
reports. It's just the High Kernel Mapping that we care about.
Addresses outside that range are less of a leak. Excellent, then GDT
may not be a problem. Whew.

Does the v2 IDT patch look okay, BTW?

-Kees

--
Kees Cook
Chrome OS Security