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From:   Marco Elver <elver@google.com>
Date:   Mon, 20 Jun 2022 15:39:48 +0200
Message-ID: <CANpmjNO_DqF+=HMQ+j9uL7qeO4a7FGy1Vuzs=pHhpQVC_is9Pw@mail.gmail.com>
Subject: Re: [PATCH 08/32] kasan: introduce kasan_init_object_meta
To:     andrey.konovalov@linux.dev
Cc:     Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        kasan-dev@googlegroups.com, Peter Collingbourne <pcc@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Florian Mayer <fmayer@google.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrey Konovalov <andreyknvl@google.com>
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On Mon, 13 Jun 2022 at 22:16, <andrey.konovalov@linux.dev> wrote:
>
> From: Andrey Konovalov <andreyknvl@google.com>
>
> Add a kasan_init_object_meta() helper that initializes metadata for a slab
> object and use it in the common code.
>
> For now, the implementations of this helper are the same for the Generic
> and tag-based modes, but they will diverge later in the series.
>
> This change hides references to alloc_meta from the common code. This is
> desired as only the Generic mode will be using per-object metadata after
> this series.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Marco Elver <elver@google.com>


> ---
>  mm/kasan/common.c  | 10 +++-------
>  mm/kasan/generic.c |  9 +++++++++
>  mm/kasan/kasan.h   |  2 ++
>  mm/kasan/tags.c    |  9 +++++++++
>  4 files changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 2848c7a2402a..f0ee1c1b4b3c 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -312,13 +312,9 @@ static inline u8 assign_tag(struct kmem_cache *cache,
>  void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
>                                                 const void *object)
>  {
> -       struct kasan_alloc_meta *alloc_meta;
> -
> -       if (kasan_stack_collection_enabled()) {
> -               alloc_meta = kasan_get_alloc_meta(cache, object);
> -               if (alloc_meta)
> -                       __memset(alloc_meta, 0, sizeof(*alloc_meta));
> -       }
> +       /* Initialize per-object metadata if it is present. */
> +       if (kasan_stack_collection_enabled())
> +               kasan_init_object_meta(cache, object);
>
>         /* Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS */
>         object = set_tag(object, assign_tag(cache, object, true));
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index f212b9ae57b5..5462ddbc21e6 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -328,6 +328,15 @@ DEFINE_ASAN_SET_SHADOW(f3);
>  DEFINE_ASAN_SET_SHADOW(f5);
>  DEFINE_ASAN_SET_SHADOW(f8);
>
> +void kasan_init_object_meta(struct kmem_cache *cache, const void *object)
> +{
> +       struct kasan_alloc_meta *alloc_meta;
> +
> +       alloc_meta = kasan_get_alloc_meta(cache, object);
> +       if (alloc_meta)
> +               __memset(alloc_meta, 0, sizeof(*alloc_meta));
> +}
> +
>  static void __kasan_record_aux_stack(void *addr, bool can_alloc)
>  {
>         struct slab *slab = kasan_addr_to_slab(addr);
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 4005da62a1e1..751c3b17749a 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -278,6 +278,8 @@ void kasan_report_invalid_free(void *object, unsigned long ip);
>  struct page *kasan_addr_to_page(const void *addr);
>  struct slab *kasan_addr_to_slab(const void *addr);
>
> +void kasan_init_object_meta(struct kmem_cache *cache, const void *object);
> +
>  depot_stack_handle_t kasan_save_stack(gfp_t flags, bool can_alloc);
>  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);
> diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
> index 7b1fc8e7c99c..2e200969a4b8 100644
> --- a/mm/kasan/tags.c
> +++ b/mm/kasan/tags.c
> @@ -17,6 +17,15 @@
>
>  #include "kasan.h"
>
> +void kasan_init_object_meta(struct kmem_cache *cache, const void *object)
> +{
> +       struct kasan_alloc_meta *alloc_meta;
> +
> +       alloc_meta = kasan_get_alloc_meta(cache, object);
> +       if (alloc_meta)
> +               __memset(alloc_meta, 0, sizeof(*alloc_meta));
> +}
> +
>  void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
>  {
>         struct kasan_alloc_meta *alloc_meta;
> --
> 2.25.1
>
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