Re: [PATCH 04/20] mm: zswap: warn when referencing a dead entry

[Nhat Pham]

On Mon, Jan 29, 2024 at 5:42 PM Johannes Weiner <hannes@xxxxxxxxxxx> wrote:
>
> Put a standard sanity check on zswap_entry_get() for UAF scenario.
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> ---
>  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 *entry)
>  /* 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@xxxxxxxxx>