linux-kernel - Re: [PATCH] PM: hibernate: Fix crash when freeing invalid crypto compressor

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Message-ID: <CAJZ5v0hn1E=tWVoG7nKsD3_KGygkaGpeSoQ4JsMaJNgugT_Tnw@mail.gmail.com>
Date: Fri, 26 Dec 2025 14:20:59 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Malaya Kumar Rout <mrout@...hat.com>
Cc: linux-kernel@...r.kernel.org, malayarout91@...il.com, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>, Pavel Machek <pavel@...nel.org>, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH] PM: hibernate: Fix crash when freeing invalid crypto compressor

On Wed, Dec 24, 2025 at 7:21 PM Malaya Kumar Rout <mrout@...hat.com> wrote:
>
> When crypto_alloc_acomp() fails, it returns an ERR_PTR value, not NULL.
> The cleanup code in save_compressed_image() and load_compressed_image()
> unconditionally calls crypto_free_acomp() without checking for ERR_PTR,
> which causes crypto_acomp_tfm() to dereference an invalid pointer and
> crash the kernel.
>
> This can be triggered when the compression algorithm is unavailable
> (e.g., CONFIG_CRYPTO_LZO not enabled).
>
> Fix by adding IS_ERR_OR_NULL() checks before calling crypto_free_acomp()
> and acomp_request_free(), similar to the existing kthread_stop() check.
>
> Signed-off-by: Malaya Kumar Rout <mrout@...hat.com>

I think that it should be possible to find a specific commit fixed by
this and provide a Fixes: tag pointing to it.

Can you please do so?

> ---
>  kernel/power/swap.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index 33a186373bef..8ee2fa995580 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -902,8 +902,10 @@ static int save_compressed_image(struct swap_map_handle *handle,
>                 for (thr = 0; thr < nr_threads; thr++) {
>                         if (data[thr].thr)
>                                 kthread_stop(data[thr].thr);
> -                       acomp_request_free(data[thr].cr);
> -                       crypto_free_acomp(data[thr].cc);
> +                       if (data[thr].cr)
> +                               acomp_request_free(data[thr].cr);
> +                       if (!IS_ERR_OR_NULL(data[thr].cc))
> +                               crypto_free_acomp(data[thr].cc);
>                 }
>                 vfree(data);
>         }
> @@ -1499,8 +1501,10 @@ static int load_compressed_image(struct swap_map_handle *handle,
>                 for (thr = 0; thr < nr_threads; thr++) {
>                         if (data[thr].thr)
>                                 kthread_stop(data[thr].thr);
> -                       acomp_request_free(data[thr].cr);
> -                       crypto_free_acomp(data[thr].cc);
> +                       if (data[thr].cr)
> +                               acomp_request_free(data[thr].cr);
> +                       if (!IS_ERR_OR_NULL(data[thr].cc))
> +                               crypto_free_acomp(data[thr].cc);
>                 }
>                 vfree(data);
>         }
> --
> 2.51.0
>