Re: [PATCH v2 17/33] mm: kfence: Disable KMSAN when checking the canary

[Alexander Potapenko]

On Tue, Nov 21, 2023 at 11:02 PM Ilya Leoshkevich <iii@xxxxxxxxxxxxx> wrote:
>
> KMSAN warns about check_canary() accessing the canary.
>
> The reason is that, even though set_canary() is properly instrumented
> and sets shadow, slub explicitly poisons the canary's address range
> afterwards.
>
> Unpoisoning the canary is not the right thing to do: only
> check_canary() is supposed to ever touch it. Instead, disable KMSAN
> checks around canary read accesses.
>
> Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx>