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Subject: Re: [PATCH v9 01/20] kasan, mm: change hooks signatures
To:     Andrey Konovalov <andreyknvl@google.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Christoph Lameter <cl@linux.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Dave Martin <dave.martin@arm.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        "Eric W . Biederman" <ebiederm@xmission.com>,
        Ingo Molnar <mingo@kernel.org>,
        Paul Lawrence <paullawrence@google.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Arnd Bergmann <arnd@arndb.de>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        kasan-dev@googlegroups.com, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-sparse@vger.kernel.org, linux-mm@kvack.org,
        linux-kbuild@vger.kernel.org
Cc:     Kostya Serebryany <kcc@google.com>,
        Evgeniy Stepanov <eugenis@google.com>,
        Lee Smith <Lee.Smith@arm.com>,
        Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
        Jacob Bramley <Jacob.Bramley@arm.com>,
        Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
        Jann Horn <jannh@google.com>,
        Mark Brand <markbrand@google.com>,
        Chintan Pandya <cpandya@codeaurora.org>,
        Vishwath Mohan <vishwath@google.com>
References: <cover.1537542735.git.andreyknvl@google.com>
 <37b1d7e7c372b60e2323b33bf2e57d4e3409df0b.1537542735.git.andreyknvl@google.com>
From:   Andrey Ryabinin <aryabinin@virtuozzo.com>
Message-ID: <64a7030a-d6bf-3b52-aa7d-dbb1b25a7bc8@virtuozzo.com>
Date:   Wed, 31 Oct 2018 19:33:34 +0300
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On 09/21/2018 06:13 PM, Andrey Konovalov wrote:
> Tag-based KASAN changes the value of the top byte of pointers returned
> from the kernel allocation functions (such as kmalloc). This patch updates
> KASAN hooks signatures and their usage in SLAB and SLUB code to reflect
> that.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
>  include/linux/kasan.h | 43 +++++++++++++++++++++++++++++--------------
>  mm/kasan/kasan.c      | 30 ++++++++++++++++++------------
>  mm/slab.c             | 12 ++++++------
>  mm/slab.h             |  2 +-
>  mm/slab_common.c      |  4 ++--
>  mm/slub.c             | 15 +++++++--------
>  6 files changed, 63 insertions(+), 43 deletions(-)
> 
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 46aae129917c..52c86a568a4e 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -51,16 +51,16 @@ void kasan_cache_shutdown(struct kmem_cache *cache);
>  void kasan_poison_slab(struct page *page);
>  void kasan_unpoison_object_data(struct kmem_cache *cache, void *object);
>  void kasan_poison_object_data(struct kmem_cache *cache, void *object);
> -void kasan_init_slab_obj(struct kmem_cache *cache, const void *object);
> +void *kasan_init_slab_obj(struct kmem_cache *cache, const void *object);
>  
> -void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags);
> +void *kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags);
>  void kasan_kfree_large(void *ptr, unsigned long ip);
>  void kasan_poison_kfree(void *ptr, unsigned long ip);
> -void kasan_kmalloc(struct kmem_cache *s, const void *object, size_t size,
> +void *kasan_kmalloc(struct kmem_cache *s, const void *object, size_t size,
>  		  gfp_t flags);

This patch missed couple call-sites, in kmem_cache_alloc_trace() and kmem_cache_alloc_node_trace() in include/linux/slab.h,
the return value of kasan_kmalloc() is ignored. Probably worth adding __must_check to functions like this.

Once that fixed you can add Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
here and to the rest of the patches. They look fine me.