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From: Andrey Konovalov <andreyknvl@gmail.com>
To: Jann Horn <jannh@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	 Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	 Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	 Alexander Potapenko <glider@google.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	 Andrew Morton <akpm@linux-foundation.org>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	 Hyeonggon Yoo <42.hyeyoo@gmail.com>,
	kasan-dev@googlegroups.com,  linux-kernel@vger.kernel.org,
	linux-mm@kvack.org,  linux-hardening@vger.kernel.org,
	kernel-hardening@lists.openwall.com
Subject: Re: [PATCH] slub: Introduce CONFIG_SLUB_RCU_DEBUG
Date: Sat, 16 Sep 2023 18:18:54 +0200	[thread overview]
Message-ID: <CA+fCnZeyS=wr-u4FgJmGLXujcat=oQ+jo-NAt1TtSa_tLEstSg@mail.gmail.com> (raw)
In-Reply-To: <CAG48ez34DN_xsj7hio8epvoE8hM3F_xFoqwWYM-_LVZb39_e9A@mail.gmail.com>

On Mon, Aug 28, 2023 at 4:40 PM Jann Horn <jannh@google.com> wrote:
>
> > Can't we unpoision this rcu_head right before call_rcu() and repoison
> > after receiving the callback?
>
> Yeah, I think that should work. It looks like currently
> kasan_unpoison() is exposed in include/linux/kasan.h but
> kasan_poison() is not, and its inline definition probably means I
> can't just move it out of mm/kasan/kasan.h into include/linux/kasan.h;
> do you have a preference for how I should handle this? Hmm, and it
> also looks like code outside of mm/kasan/ anyway wouldn't know what
> are valid values for the "value" argument to kasan_poison().
> I also have another feature idea that would also benefit from having
> something like kasan_poison() available in include/linux/kasan.h, so I
> would prefer that over adding another special-case function inside
> KASAN for poisoning this piece of slab metadata...

This is a problem only for the Generic mode, right? You already call
kasan_reset_tag on the rcu_head, which should suppress the reporting
for the tag-based modes.

If so, would it be possible to reuse metadata_access_enable/disable?
They are used for accessing slub_debug metadata and seem to fit nicely
with this case as well.

I also second Macro's comment to add a test for the new functionality.

Thanks for working on this!

  parent reply	other threads:[~2023-09-16 16:31 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-25 21:14 [PATCH] slub: Introduce CONFIG_SLUB_RCU_DEBUG Jann Horn
2023-08-26  3:32 ` Dmitry Vyukov
2023-08-28 14:39   ` Jann Horn
2023-09-11  9:50     ` Dmitry Vyukov
2023-09-16 16:18     ` Andrey Konovalov [this message]
2023-09-05  7:57 ` kernel test robot
2023-09-11 11:51 ` Marco Elver

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