linux-kernel - Re: [PATCH] mm/zswap: fix error pointer free in zswap_cpu_comp

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Message-ID: <prkvck4d7m5tra7sbonygvd6mtmdqj7lyj5wps4mjwkvunpkol@lm5sefrcedgd>
Date: Fri, 2 Jan 2026 16:43:32 +0000
From: Yosry Ahmed <yosry.ahmed@...ux.dev>
To: Pavel Butsykin <pbutsykin@...udlinux.com>
Cc: hannes@...xchg.org, nphamcs@...il.com, chengming.zhou@...ux.dev, 
	akpm@...ux-foundation.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	stable@...r.kernel.org
Subject: Re: [PATCH] mm/zswap: fix error pointer free in
 zswap_cpu_comp_prepare()

On Wed, Dec 31, 2025 at 11:46:38AM +0400, Pavel Butsykin wrote:
> crypto_alloc_acomp_node() may return ERR_PTR(), but the fail path checks
> only for NULL and can pass an error pointer to crypto_free_acomp().
> Use IS_ERR_OR_NULL() to only free valid acomp instances.
> 
> Fixes: 779b9955f643 ("mm: zswap: move allocations during CPU init outside the lock")
> Cc: stable@...r.kernel.org
> Signed-off-by: Pavel Butsykin <pbutsykin@...udlinux.com>

Thanks for the fix!

Acked-by: Yosry Ahmed <yosry.ahmed@...ux.dev>

> ---
>  mm/zswap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 5d0f8b13a958..ac9b7a60736b 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -787,7 +787,7 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
>  	return 0;
>  
>  fail:
> -	if (acomp)
> +	if (!IS_ERR_OR_NULL(acomp))
>  		crypto_free_acomp(acomp);
>  	kfree(buffer);
>  	return ret;
> -- 
> 2.52.0
>