Re: [PATCH v4 09/10] x86-64: Randomize int 0xcc magic al values at boot

[Andrew Lutomirski]

On Tue, May 31, 2011 at 11:56 AM, Andrew Lutomirski <luto@xxxxxxx> wrote:
> We could scrap int 0xcc entirely and emulate on page fault, but that
> is slower and has other problems (like breaking anything that thinks
> it can look at a call target in a binary and dereference that
> address).
>
> Here's a possibly dumb/evil idea:
>
> Put real syscalls in the vsyscall page but mark the page NX.  Then
> emulate the vsyscalls on the PF_INSTR fault when userspace jumps to
> the correct address but send SIGSEGV for the wrong address.
>
> Down side: it's even more complexity for the same silly case.

Scratch that.  It's incompatible with keeping time() fast for now.

>
> --Andy
>
>>
>> Thanks,
>>
>>        Ingo
>>
>
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