linux-kernel - Re: [PATCH] ACPI: custom_method: fix a possible memory leak

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Date:   Sun, 12 Nov 2023 15:43:50 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     "shiqiang.deng" <shiqiang.deng213@...il.com>
Cc:     rafael@...nel.org, lenb@...nel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI: custom_method: fix a possible memory leak

On Sat, Nov 11, 2023 at 2:25 PM shiqiang.deng
<shiqiang.deng213@...il.com> wrote:
>
> In the cm_write() function, memory is allocated,
> and at the end of the function when uncopied_bytes is 0,
> the memory is freed. If uncopied_bytes is not equal to 0,
> a memory leak occurs.
>
> Signed-off-by: shiqiang.deng <shiqiang.deng213@...il.com>
> ---
>  drivers/acpi/custom_method.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c
> index d39a9b474727..5103c7c3a6ce 100644
> --- a/drivers/acpi/custom_method.c
> +++ b/drivers/acpi/custom_method.c
> @@ -77,6 +77,9 @@ static ssize_t cm_write(struct file *file, const char __user *user_buf,
>                 if (ACPI_FAILURE(status))
>                         return -EINVAL;
>                 add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
> +       } else {
> +               kfree(buf);
> +               buf = NULL;
>         }
>
>         return count;
> --

That was discussed in the past and I still would rather drop this I/F
completely instead of patching it for minor issues.