Re: [PATCH 07/32] kasan: introduce kasan_get_alloc_track

[Marco Elver <elver@google.com>]

On Mon, 13 Jun 2022 at 22:16, <andrey.konovalov@linux.dev> wrote:
>
> From: Andrey Konovalov <andreyknvl@google.com>
>
> Add a kasan_get_alloc_track() helper that fetches alloc_track for a slab
> object and use this helper in the common reporting 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 reporting 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/generic.c | 14 +++++++++++++-
>  mm/kasan/kasan.h   |  4 +++-
>  mm/kasan/report.c  |  8 ++++----
>  mm/kasan/tags.c    | 14 +++++++++++++-
>  4 files changed, 33 insertions(+), 7 deletions(-)
>
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index 98c451a3b01f..f212b9ae57b5 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -381,8 +381,20 @@ void kasan_save_free_info(struct kmem_cache *cache,
>         *(u8 *)kasan_mem_to_shadow(object) = KASAN_SLAB_FREETRACK;
>  }
>
> +struct kasan_track *kasan_get_alloc_track(struct kmem_cache *cache,
> +                                               void *object)
> +{
> +       struct kasan_alloc_meta *alloc_meta;
> +
> +       alloc_meta = kasan_get_alloc_meta(cache, object);
> +       if (!alloc_meta)
> +               return NULL;
> +
> +       return &alloc_meta->alloc_track;
> +}
> +
>  struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
> -                               void *object, u8 tag)
> +                                               void *object, u8 tag)
>  {
>         if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_SLAB_FREETRACK)
>                 return NULL;
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index bcea5ed15631..4005da62a1e1 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -282,8 +282,10 @@ 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);
>  void kasan_save_free_info(struct kmem_cache *cache, void *object, u8 tag);
> +struct kasan_track *kasan_get_alloc_track(struct kmem_cache *cache,
> +                                               void *object);
>  struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
> -                               void *object, u8 tag);
> +                                               void *object, u8 tag);
>
>  #if defined(CONFIG_KASAN_GENERIC) && \
>         (defined(CONFIG_SLAB) || defined(CONFIG_SLUB))
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 35dd8aeb115c..f951fd39db74 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -251,12 +251,12 @@ static void describe_object_addr(struct kmem_cache *cache, void *object,
>  static void describe_object_stacks(struct kmem_cache *cache, void *object,
>                                         const void *addr, u8 tag)
>  {
> -       struct kasan_alloc_meta *alloc_meta;
> +       struct kasan_track *alloc_track;
>         struct kasan_track *free_track;
>
> -       alloc_meta = kasan_get_alloc_meta(cache, object);
> -       if (alloc_meta) {
> -               print_track(&alloc_meta->alloc_track, "Allocated");
> +       alloc_track = kasan_get_alloc_track(cache, object);
> +       if (alloc_track) {
> +               print_track(alloc_track, "Allocated");
>                 pr_err("\n");
>         }
>
> diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
> index e0e5de8ce834..7b1fc8e7c99c 100644
> --- a/mm/kasan/tags.c
> +++ b/mm/kasan/tags.c
> @@ -38,8 +38,20 @@ void kasan_save_free_info(struct kmem_cache *cache,
>         kasan_set_track(&alloc_meta->free_track, GFP_NOWAIT);
>  }
>
> +struct kasan_track *kasan_get_alloc_track(struct kmem_cache *cache,
> +                                               void *object)
> +{
> +       struct kasan_alloc_meta *alloc_meta;
> +
> +       alloc_meta = kasan_get_alloc_meta(cache, object);
> +       if (!alloc_meta)
> +               return NULL;
> +
> +       return &alloc_meta->alloc_track;
> +}
> +
>  struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
> -                               void *object, u8 tag)
> +                                               void *object, u8 tag)
>  {
>         struct kasan_alloc_meta *alloc_meta;
>
> --
> 2.25.1
>
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