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References: <20240130014208.565554-1-hannes@cmpxchg.org> <20240130014208.565554-5-hannes@cmpxchg.org>
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From: Nhat Pham <nphamcs@gmail.com>
Date: Tue, 30 Jan 2024 08:27:55 -0800
Message-ID: <CAKEwX=MjJRaHKJYELY7JtqPGxACMvpDp_bFx31zR68XeYZGsng@mail.gmail.com>
Subject: Re: [PATCH 04/20] mm: zswap: warn when referencing a dead entry
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, Yosry Ahmed <yosryahmed@google.com>, 
	Chengming Zhou <zhouchengming@bytedance.com>, linux-mm@kvack.org, 
	linux-kernel@vger.kernel.org
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On Mon, Jan 29, 2024 at 5:42=E2=80=AFPM Johannes Weiner <hannes@cmpxchg.org=
> wrote:
>
> Put a standard sanity check on zswap_entry_get() for UAF scenario.
>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> ---
>  mm/zswap.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 9f05282efe3c..0c6adaf2fdb6 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -542,6 +542,7 @@ static void zswap_entry_free(struct zswap_entry *entr=
y)
>  /* caller must hold the tree lock */
>  static void zswap_entry_get(struct zswap_entry *entry)
>  {
> +       WARN_ON_ONCE(!entry->refcount);
>         entry->refcount++;
>  }
>
> --
> 2.43.0
>

Reviewed-by: Nhat Pham <nphamcs@gmail.com>