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Thu, 03 Dec 2020 11:50:32 -0800 (PST) Received: from [10.9.0.26] ([185.248.161.177]) by smtp.gmail.com with ESMTPSA id 20sm439140wmk.16.2020.12.03.11.50.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 03 Dec 2020 11:50:31 -0800 (PST) Reply-To: alex.popov@linux.com Subject: Re: [PATCH RFC v2 2/6] mm/slab: Perform init_on_free earlier To: Alexander Potapenko Cc: Kees Cook , Jann Horn , Will Deacon , Andrey Ryabinin , Dmitry Vyukov , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Masahiro Yamada , Masami Hiramatsu , Steven Rostedt , Peter Zijlstra , Krzysztof Kozlowski , Patrick Bellasi , David Howells , Eric Biederman , Johannes Weiner , Laura Abbott , Arnd Bergmann , Greg Kroah-Hartman , Daniel Micay , Andrey Konovalov , Matthew Wilcox , Pavel Machek , Valentin Schneider , kasan-dev , Linux Memory Management List , Kernel Hardening , LKML , notify@kernel.org References: <20200929183513.380760-1-alex.popov@linux.com> <20200929183513.380760-3-alex.popov@linux.com> From: Alexander Popov Message-ID: <1772bc7d-e87f-0f62-52a8-e9d9ac99f5e3@linux.com> Date: Thu, 3 Dec 2020 22:50:27 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 30.09.2020 15:50, Alexander Potapenko wrote: > On Tue, Sep 29, 2020 at 8:35 PM Alexander Popov wrote: >> >> Currently in CONFIG_SLAB init_on_free happens too late, and heap >> objects go to the heap quarantine being dirty. Lets move memory >> clearing before calling kasan_slab_free() to fix that. >> >> Signed-off-by: Alexander Popov > Reviewed-by: Alexander Potapenko Hello! Can this particular patch be considered for the mainline kernel? Note: I summarized the results of the experiment with the Linux kernel heap quarantine in a short article, for future reference: https://a13xp0p0v.github.io/2020/11/30/slab-quarantine.html Best regards, Alexander >> --- >> mm/slab.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/mm/slab.c b/mm/slab.c >> index 3160dff6fd76..5140203c5b76 100644 >> --- a/mm/slab.c >> +++ b/mm/slab.c >> @@ -3414,6 +3414,9 @@ static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac) >> static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp, >> unsigned long caller) >> { >> + if (unlikely(slab_want_init_on_free(cachep))) >> + memset(objp, 0, cachep->object_size); >> + >> /* Put the object into the quarantine, don't touch it for now. */ >> if (kasan_slab_free(cachep, objp, _RET_IP_)) >> return; >> @@ -3432,8 +3435,6 @@ void ___cache_free(struct kmem_cache *cachep, void *objp, >> struct array_cache *ac = cpu_cache_get(cachep); >> >> check_irq_off(); >> - if (unlikely(slab_want_init_on_free(cachep))) >> - memset(objp, 0, cachep->object_size); >> kmemleak_free_recursive(objp, cachep->flags); >> objp = cache_free_debugcheck(cachep, objp, caller); >> memcg_slab_free_hook(cachep, virt_to_head_page(objp), objp); >> -- >> 2.26.2 >> > >