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Sat, 16 Sep 2023 09:19:05 -0700 (PDT) MIME-Version: 1.0 References: <20230825211426.3798691-1-jannh@google.com> In-Reply-To: From: Andrey Konovalov Date: Sat, 16 Sep 2023 18:18:54 +0200 Message-ID: Subject: Re: [PATCH] slub: Introduce CONFIG_SLUB_RCU_DEBUG To: Jann Horn Cc: Dmitry Vyukov , Andrey Ryabinin , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Alexander Potapenko , Vincenzo Frascino , Andrew Morton , Roman Gushchin , 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 5CDF2180022 X-Rspam-User: X-Stat-Signature: guau8zp5of3s49hz1w3gq9unktr6d1rn X-Rspamd-Server: rspam03 X-HE-Tag: 1694881146-283233 X-HE-Meta: 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 jTsIyLAC 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Aug 28, 2023 at 4:40=E2=80=AFPM Jann Horn 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!