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From:   Marco Elver <elver@google.com>
Date:   Tue, 12 Dec 2023 20:30:01 +0100
Message-ID: <CANpmjNNTA2qvBTLvA6Qn4HSpsWP6dmMODCFSVtLKZrZfGSAL0A@mail.gmail.com>
Subject: Re: [PATCH mm 3/4] kasan: memset free track in qlink_free
To:     andrey.konovalov@linux.dev
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Vlastimil Babka <vbabka@suse.cz>, kasan-dev@googlegroups.com,
        Evgenii Stepanov <eugenis@google.com>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Andrey Konovalov <andreyknvl@google.com>
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On Tue, 12 Dec 2023 at 01:14, <andrey.konovalov@linux.dev> wrote:
>
> From: Andrey Konovalov <andreyknvl@google.com>
>
> Instead of only zeroing out the stack depot handle when evicting the
> free stack trace in qlink_free, zero out the whole track.
>
> Do this just to produce a similar effect for alloc and free meta. The
> other fields of the free track besides the stack trace handle are
> considered invalid at this point anyway, so no harm in zeroing them out.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

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

> ---
>
> This can be squashed into "kasan: use stack_depot_put for Generic mode"
> or left standalone.
> ---
>  mm/kasan/quarantine.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
> index 265ca2bbe2dd..782e045da911 100644
> --- a/mm/kasan/quarantine.c
> +++ b/mm/kasan/quarantine.c
> @@ -157,7 +157,7 @@ static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
>         if (free_meta &&
>             *(u8 *)kasan_mem_to_shadow(object) == KASAN_SLAB_FREETRACK) {
>                 stack_depot_put(free_meta->free_track.stack);
> -               free_meta->free_track.stack = 0;
> +               __memset(&free_meta->free_track, 0, sizeof(free_meta->free_track));
>         }
>
>         /*
> --
> 2.25.1
>