linux-kernel - Re: [PATCH RFC v2 20/21] kasan: simplify assign_tag and set

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 28 Oct 2020 18:03:21 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Andrey Konovalov <andreyknvl@...gle.com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Kostya Serebryany <kcc@...gle.com>,
        Peter Collingbourne <pcc@...gle.com>,
        Serban Constantinescu <serbanc@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Elena Petrova <lenaptr@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC v2 20/21] kasan: simplify assign_tag and set_tag calls

On Thu, Oct 22, 2020 at 3:20 PM Andrey Konovalov <andreyknvl@...gle.com> wrote:
>
> set_tag() already ignores the tag for the generic mode, so just call it
> as is. Add a check for the generic mode to assign_tag(), and simplify its
> call in ____kasan_kmalloc().
>
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> Link: https://linux-review.googlesource.com/id/I18905ca78fb4a3d60e1a34a4ca00247272480438

Reviewed-by: Dmitry Vyukov <dvyukov@...gle.com>

> ---
>  mm/kasan/common.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 983383ebe32a..3cd56861eb11 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -235,6 +235,9 @@ void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
>  static u8 assign_tag(struct kmem_cache *cache, const void *object,
>                         bool init, bool keep_tag)
>  {
> +       if (IS_ENABLED(CONFIG_KASAN_GENERIC))
> +               return 0xff;
> +
>         /*
>          * 1. When an object is kmalloc()'ed, two hooks are called:
>          *    kasan_slab_alloc() and kasan_kmalloc(). We assign the
> @@ -277,8 +280,8 @@ void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
>                 __memset(alloc_meta, 0, sizeof(*alloc_meta));
>         }
>
> -       if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS))
> -               object = set_tag(object, assign_tag(cache, object, true, false));
> +       /* Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS */
> +       object = set_tag(object, assign_tag(cache, object, true, false));
>
>         return (void *)object;
>  }
> @@ -360,9 +363,7 @@ static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object,
>                                 KASAN_GRANULE_SIZE);
>         redzone_end = round_up((unsigned long)object + cache->object_size,
>                                 KASAN_GRANULE_SIZE);
> -
> -       if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS))
> -               tag = assign_tag(cache, object, false, keep_tag);
> +       tag = assign_tag(cache, object, false, keep_tag);
>
>         /*
>          * Don't unpoison the object when keeping the tag. Tag is kept for:
> --
> 2.29.0.rc1.297.gfa9743e501-goog
>