linux-kernel - Re: [PATCH 2/2] kasan: apply store-only mode in kasan kunit testcases

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Message-ID: <CA+fCnZeznLqoLsUOgB1a1TNpR9PxjZKrrVBhotpMh0KVwvzj_Q@mail.gmail.com>
Date: Tue, 12 Aug 2025 19:58:37 +0200
From: Andrey Konovalov <andreyknvl@...il.com>
To: Yeoreum Yun <yeoreum.yun@....com>
Cc: ryabinin.a.a@...il.com, glider@...gle.com, dvyukov@...gle.com, 
	vincenzo.frascino@....com, corbet@....net, catalin.marinas@....com, 
	will@...nel.org, akpm@...ux-foundation.org, scott@...amperecomputing.com, 
	jhubbard@...dia.com, pankaj.gupta@....com, leitao@...ian.org, 
	kaleshsingh@...gle.com, maz@...nel.org, broonie@...nel.org, 
	oliver.upton@...ux.dev, james.morse@....com, ardb@...nel.org, 
	hardevsinh.palaniya@...iconsignals.io, david@...hat.com, 
	yang@...amperecomputing.com, kasan-dev@...glegroups.com, 
	workflows@...r.kernel.org, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-mm@...ck.org
Subject: Re: [PATCH 2/2] kasan: apply store-only mode in kasan kunit testcases

On Tue, Aug 12, 2025 at 6:57 PM Yeoreum Yun <yeoreum.yun@....com> wrote:
>
> > Right now, KASAN tests are crafted to avoid/self-contain harmful
> > memory corruptions that they do (e.g. make sure that OOB write
> > accesses land in in-object kmalloc training space, etc.). If you turn
> > read accesses in tests into write accesses, memory corruptions caused
> > by the earlier tests will crash the kernel or the latter tests.
>
> That's why I run the store-only test when this mode is "sync"
> In case of "async/asymm" as you mention since it reports "after",
> there will be memory corruption.
>
> But in case of sync, when the MTE fault happens, it doesn't
> write to memory so, I think it's fine.

Does it not? I thought MTE gets disabled and we return from the fault
handler and let the write instruction execute. But my memory on this
is foggy. And I don't have a setup right now to test.