Re: [PATCH] x86: make IDT read-only

From: H. Peter Anvin
Date: Mon Apr 08 2013 - 18:50:27 EST


On 04/08/2013 03:43 PM, Kees Cook wrote:
> This makes the IDT unconditionally read-only. This primarily removes
> the IDT from being a target for arbitrary memory write attacks. It has
> an added benefit of also not leaking (via the "sidt" instruction) the
> kernel base offset, if it has been relocated.
>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Eric Northup <digitaleric@xxxxxxxxxx>

This isn't quite what this patch does, though, right? There is still a
writable IDT mapping at all times, which is different from a true
readonly IDT, no?

-hpa


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