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Message-ID: <432494ef-b47f-16fa-41a0-f68613f94fc4@suse.cz>
Date: Tue, 5 Dec 2023 11:16:56 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Hyeonggon Yoo <42.hyeyoo@...il.com>
Cc: David Rientjes <rientjes@...gle.com>,
Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
Alexander Potapenko <glider@...gle.com>,
Andrey Konovalov <andreyknvl@...il.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Vincenzo Frascino <vincenzo.frascino@....com>,
Marco Elver <elver@...gle.com>,
Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...nel.org>,
Shakeel Butt <shakeelb@...gle.com>,
Muchun Song <muchun.song@...ux.dev>,
Kees Cook <keescook@...omium.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com,
cgroups@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2 03/21] KASAN: remove code paths guarded by CONFIG_SLAB
On 12/5/23 05:48, Hyeonggon Yoo wrote:
> On Tue, Dec 5, 2023 at 1:27 PM Hyeonggon Yoo <42.hyeyoo@...il.com> wrote:
>>
>> On Mon, Nov 20, 2023 at 07:34:14PM +0100, Vlastimil Babka wrote:
>> > With SLAB removed and SLUB the only remaining allocator, we can clean up
>> > some code that was depending on the choice.
>> >
>> > Reviewed-by: Kees Cook <keescook@...omium.org>
>> > Reviewed-by: Marco Elver <elver@...gle.com>
>> > Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
>> > ---
>> > mm/kasan/common.c | 13 ++-----------
>> > mm/kasan/kasan.h | 3 +--
>> > mm/kasan/quarantine.c | 7 -------
>> > 3 files changed, 3 insertions(+), 20 deletions(-)
>> >
>> > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
>> > index 256930da578a..5d95219e69d7 100644
>> > --- a/mm/kasan/common.c
>> > +++ b/mm/kasan/common.c
>> > @@ -153,10 +153,6 @@ void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
>> > * 2. A cache might be SLAB_TYPESAFE_BY_RCU, which means objects can be
>> > * accessed after being freed. We preassign tags for objects in these
>> > * caches as well.
>> > - * 3. For SLAB allocator we can't preassign tags randomly since the freelist
>> > - * is stored as an array of indexes instead of a linked list. Assign tags
>> > - * based on objects indexes, so that objects that are next to each other
>> > - * get different tags.
>> > */
>> > static inline u8 assign_tag(struct kmem_cache *cache,
>> > const void *object, bool init)
>> > @@ -171,17 +167,12 @@ static inline u8 assign_tag(struct kmem_cache *cache,
>> > if (!cache->ctor && !(cache->flags & SLAB_TYPESAFE_BY_RCU))
>> > return init ? KASAN_TAG_KERNEL : kasan_random_tag();
>> >
>> > - /* For caches that either have a constructor or SLAB_TYPESAFE_BY_RCU: */
>> > -#ifdef CONFIG_SLAB
>> > - /* For SLAB assign tags based on the object index in the freelist. */
>> > - return (u8)obj_to_index(cache, virt_to_slab(object), (void *)object);
>> > -#else
>> > /*
>> > - * For SLUB assign a random tag during slab creation, otherwise reuse
>> > + * For caches that either have a constructor or SLAB_TYPESAFE_BY_RCU,
>> > + * assign a random tag during slab creation, otherwise reuse
>> > * the already assigned tag.
>> > */
>> > return init ? kasan_random_tag() : get_tag(object);
>> > -#endif
>> > }
>> >
>> > void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
>> > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
>> > index 8b06bab5c406..eef50233640a 100644
>> > --- a/mm/kasan/kasan.h
>> > +++ b/mm/kasan/kasan.h
>> > @@ -373,8 +373,7 @@ void kasan_set_track(struct kasan_track *track, gfp_t flags);
>> > void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags);
>> > void kasan_save_free_info(struct kmem_cache *cache, void *object);
>> >
>> > -#if defined(CONFIG_KASAN_GENERIC) && \
>> > - (defined(CONFIG_SLAB) || defined(CONFIG_SLUB))
>> > +#ifdef CONFIG_KASAN_GENERIC
>> > bool kasan_quarantine_put(struct kmem_cache *cache, void *object);
>> > void kasan_quarantine_reduce(void);
>> > void kasan_quarantine_remove_cache(struct kmem_cache *cache);
>> > diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
>> > index ca4529156735..138c57b836f2 100644
>> > --- a/mm/kasan/quarantine.c
>> > +++ b/mm/kasan/quarantine.c
>> > @@ -144,10 +144,6 @@ static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
>> > {
>> > void *object = qlink_to_object(qlink, cache);
>> > struct kasan_free_meta *meta = kasan_get_free_meta(cache, object);
>> > - unsigned long flags;
>> > -
>> > - if (IS_ENABLED(CONFIG_SLAB))
>> > - local_irq_save(flags);
>> >
>> > /*
>> > * If init_on_free is enabled and KASAN's free metadata is stored in
>> > @@ -166,9 +162,6 @@ static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
>> > *(u8 *)kasan_mem_to_shadow(object) = KASAN_SLAB_FREE;
>> >
>> > ___cache_free(cache, object, _THIS_IP_);
>> > -
>> > - if (IS_ENABLED(CONFIG_SLAB))
>> > - local_irq_restore(flags);
>> > }
>> >
>> > static void qlist_free_all(struct qlist_head *q, struct kmem_cache *cache)
>>
>> Looks good to me,
>> Reviewed-by: Hyeonggon Yoo <42.hyeyoo@...il.com>
Thanks!
> nit: Some KASAN tests depends on SLUB, but as now it's the only allocator
> KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_SLUB); in
> mm/kasan/kasan_test.c can be removed
Hmm I see, but will rather also leave it for later cleanup at this point,
thanks!
>>
>> >
>> > --
>> > 2.42.1
>> >
>> >
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