On 11/02/2019 21:59, Andrey Konovalov wrote:
> Right now we call kmemleak hooks before assigning tags to pointers in
> KASAN hooks. As a result, when an objects gets allocated, kmemleak sees
> a differently tagged pointer, compared to the one it sees when the object
> gets freed. Fix it by calling KASAN hooks before kmemleak's ones.
>

Nit: Could you please add comments to the the code? It should prevent that the
code gets refactored in future, reintroducing the same issue.

> Reported-by: Qian Cai <c...@lca.pw>
> Signed-off-by: Andrey Konovalov <andreyk...@google.com>
> ---
>  mm/slab.h        | 6 ++----
>  mm/slab_common.c | 2 +-
>  mm/slub.c        | 3 ++-
>  3 files changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/slab.h b/mm/slab.h
> index 4190c24ef0e9..638ea1b25d39 100644
> --- a/mm/slab.h
> +++ b/mm/slab.h
> @@ -437,11 +437,9 @@ static inline void slab_post_alloc_hook(struct 
> kmem_cache *s, gfp_t flags,
>  
>       flags &= gfp_allowed_mask;
>       for (i = 0; i < size; i++) {
> -             void *object = p[i];
> -
> -             kmemleak_alloc_recursive(object, s->object_size, 1,
> +             p[i] = kasan_slab_alloc(s, p[i], flags);
> +             kmemleak_alloc_recursive(p[i], s->object_size, 1,
>                                        s->flags, flags);
> -             p[i] = kasan_slab_alloc(s, object, flags);
>       }
>  
>       if (memcg_kmem_enabled())
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 81732d05e74a..fe524c8d0246 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -1228,8 +1228,8 @@ void *kmalloc_order(size_t size, gfp_t flags, unsigned 
> int order)
>       flags |= __GFP_COMP;
>       page = alloc_pages(flags, order);
>       ret = page ? page_address(page) : NULL;
> -     kmemleak_alloc(ret, size, 1, flags);
>       ret = kasan_kmalloc_large(ret, size, flags);
> +     kmemleak_alloc(ret, size, 1, flags);
>       return ret;
>  }
>  EXPORT_SYMBOL(kmalloc_order);
> diff --git a/mm/slub.c b/mm/slub.c
> index 1e3d0ec4e200..4a3d7686902f 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1374,8 +1374,9 @@ static inline void dec_slabs_node(struct kmem_cache *s, 
> int node,
>   */
>  static inline void *kmalloc_large_node_hook(void *ptr, size_t size, gfp_t 
> flags)
>  {
> +     ptr = kasan_kmalloc_large(ptr, size, flags);
>       kmemleak_alloc(ptr, size, 1, flags);
> -     return kasan_kmalloc_large(ptr, size, flags);
> +     return ptr;
>  }
>  
>  static __always_inline void kfree_hook(void *x)
> 

-- 
Regards,
Vincenzo

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