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Tue, 30 Jul 2024 11:29:09 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id j0SsMYXOqGZ6NwAAD6G6ig (envelope-from ); Tue, 30 Jul 2024 11:29:09 +0000 Message-ID: <6ae22d49-7dfd-44d4-8720-fd2903a05fee@suse.cz> Date: Tue, 30 Jul 2024 13:30:47 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 2/2] slub: Introduce CONFIG_SLUB_RCU_DEBUG To: Jann Horn , Andrey Ryabinin , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Marco Elver , kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20240730-kasan-tsbrcu-v5-0-48d3cbdfccc5@google.com> <20240730-kasan-tsbrcu-v5-2-48d3cbdfccc5@google.com> From: Vlastimil Babka Content-Language: en-US In-Reply-To: <20240730-kasan-tsbrcu-v5-2-48d3cbdfccc5@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Queue-Id: C8B0540023 X-Stat-Signature: 351zxchfyosikyoqp5s8jcpu9m66mz6n X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1722338952-119815 X-HE-Meta: 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 Pd8uXn6A sRdBPMkSM69HkRoDPsNxbjV458mQg9egfld9jFto4o9IAMuVSjdCzGQ8ngW94J5joJbcMRgb1t2bIZRPLp0MDEWMnbVUY2EwpNGPE/4EnOgA0ViszUXm+s4VW5apRo9AJuLKo6S4CkZuST5vP0laLouOYRMRsuKm7gcCxzuNzm9e2bALXSKHmAWAAyWcFwR4QqXyUECJptKFW6YNAf+bXKfne6ZIrSmgi9uHGybYodyFeXcqNjKn+dFoTmOoGv3h2h3pqz8B3hhurMNafC08nPgBeAp1COVg4Z72qaqKbiQSlr0OKKPHy+LWMFIph2md4QAxLDYcVraOLKHltehJ2tZRVNH3KZhBO6AD6PmqsPgLWLAi4bjdabt9ZpANQwHxtgU/uFt3wMnA20wRhAZdEcWarvg== 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: List-Subscribe: List-Unsubscribe: On 7/30/24 1:06 PM, Jann Horn wrote: > Currently, KASAN is unable to catch use-after-free in SLAB_TYPESAFE_BY_RCU > slabs because use-after-free is allowed within the RCU grace period by > design. > > Add a SLUB debugging feature which RCU-delays every individual > kmem_cache_free() before either actually freeing the object or handing it > off to KASAN, and change KASAN to poison freed objects as normal when this > option is enabled. > > For now I've configured Kconfig.debug to default-enable this feature in the > KASAN GENERIC and SW_TAGS modes; I'm not enabling it by default in HW_TAGS > mode because I'm not sure if it might have unwanted performance degradation > effects there. > > Note that this is mostly useful with KASAN in the quarantine-based GENERIC > mode; SLAB_TYPESAFE_BY_RCU slabs are basically always also slabs with a > ->ctor, and KASAN's assign_tag() currently has to assign fixed tags for > those, reducing the effectiveness of SW_TAGS/HW_TAGS mode. > (A possible future extension of this work would be to also let SLUB call > the ->ctor() on every allocation instead of only when the slab page is > allocated; then tag-based modes would be able to assign new tags on every > reallocation.) > > Signed-off-by: Jann Horn Acked-by: Vlastimil Babka #slab