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Date: Thu, 3 Dec 2020 22:50:27 +0300
From: Alexander Popov <alex.popov@...ux.com>
To: Alexander Potapenko <glider@...gle.com>
Cc: Kees Cook <keescook@...omium.org>, Jann Horn <jannh@...gle.com>,
Will Deacon <will@...nel.org>, Andrey Ryabinin <aryabinin@...tuozzo.com>,
Dmitry Vyukov <dvyukov@...gle.com>, Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>, David Rientjes <rientjes@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
Masahiro Yamada <masahiroy@...nel.org>,
Masami Hiramatsu <mhiramat@...nel.org>, Steven Rostedt
<rostedt@...dmis.org>, Peter Zijlstra <peterz@...radead.org>,
Krzysztof Kozlowski <krzk@...nel.org>,
Patrick Bellasi <patrick.bellasi@....com>,
David Howells <dhowells@...hat.com>, Eric Biederman <ebiederm@...ssion.com>,
Johannes Weiner <hannes@...xchg.org>, Laura Abbott <labbott@...hat.com>,
Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Daniel Micay <danielmicay@...il.com>,
Andrey Konovalov <andreyknvl@...gle.com>,
Matthew Wilcox <willy@...radead.org>, Pavel Machek <pavel@...x.de>,
Valentin Schneider <valentin.schneider@....com>,
kasan-dev <kasan-dev@...glegroups.com>,
Linux Memory Management List <linux-mm@...ck.org>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>,
LKML <linux-kernel@...r.kernel.org>, notify@...nel.org
Subject: Re: [PATCH RFC v2 2/6] mm/slab: Perform init_on_free earlier
On 30.09.2020 15:50, Alexander Potapenko wrote:
> On Tue, Sep 29, 2020 at 8:35 PM Alexander Popov <alex.popov@...ux.com> 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 <alex.popov@...ux.com>
> Reviewed-by: Alexander Potapenko <glider@...gle.com>
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
>>
>
>
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