Re: Re: [PATCH 1/1] kasan: Support for r/w instrumentation control

[Dmitry Vyukov]

On Mon, Dec 12, 2016 at 11:29 AM, Vaneet Narang <v.narang@xxxxxxxxxxx> wrote:
>  Hi,
>
>> Do you actually hit an issue with image size? In what context?
>> Do you use inline/outline instrumentation? Does switching to the other
>> option help?
>
> Memory access with KASAN enabled Image has overhead in terms of cpu execution.
> Sometimes we are not able to reproduce race condition issues with these overhead in
> place. So user should have control atleast over read instrumentation.

Don't you want to disable KASAN entirely in such case?


>> Does it make sense to ever disable writes? I assume that you are
>
> Write instrumentation control is majorly kept to be inline with ASAN for user space
> applications.
> Also write is sometimes useful when uImage is already sanitized and some corruption
> is done by kernel modules by doing some direct memory access then both read / write sanity of uImage
> can be avoided.

But then you don't need KASAN at all.


>> disabling reads, right?
>> Disabling both certainly does not make sense.