linux-kernel - Re: [PATCH] vfio/platform: Remove the ACPI buffer memory to fix memory leak

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Message-ID: <20221129125238.4ecdb3f0.alex.williamson@redhat.com>
Date:   Tue, 29 Nov 2022 12:52:38 -0700
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Hanjun Guo <guohanjun@...wei.com>
Cc:     Eric Auger <eric.auger@...hat.com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Sinan Kaya <okaya@...eaurora.org>
Subject: Re: [PATCH] vfio/platform: Remove the ACPI buffer memory to fix
 memory leak

On Tue, 22 Nov 2022 19:29:58 +0800
Hanjun Guo <guohanjun@...wei.com> wrote:

> The ACPI buffer memory (buffer.pointer) returned by acpi_evaluate_object()
> is not used after the call of _RST method, so it leads to memory leak.
> 
> For the calling of ACPI _RST method, we don't need to pass a buffer
> for acpi_evaluate_object(), we can just pass NULL and remove the ACPI
> buffer memory in vfio_platform_acpi_call_reset(), then we don't need to
> free the memory and no memory leak.
> 
> Fixes: d30daa33ec1d ("vfio: platform: call _RST method when using ACPI")
> Signed-off-by: Hanjun Guo <guohanjun@...wei.com>
> ---
>  drivers/vfio/platform/vfio_platform_common.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index 55dc4f4..1a0a238 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -72,12 +72,11 @@ static int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev,
>  				  const char **extra_dbg)
>  {
>  #ifdef CONFIG_ACPI
> -	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
>  	struct device *dev = vdev->device;
>  	acpi_handle handle = ACPI_HANDLE(dev);
>  	acpi_status acpi_ret;
>  
> -	acpi_ret = acpi_evaluate_object(handle, "_RST", NULL, &buffer);
> +	acpi_ret = acpi_evaluate_object(handle, "_RST", NULL, NULL);
>  	if (ACPI_FAILURE(acpi_ret)) {
>  		if (extra_dbg)
>  			*extra_dbg = acpi_format_exception(acpi_ret);

An identical change was already posted and accepted into the vfio next
branch, see:

https://lore.kernel.org/all/20221018152825.891032-1-rafaelmendsr@gmail.com/

In linux-next as:

e67e070632a6 ("vfio: platform: Do not pass return buffer to ACPI _RST method")

Thanks,
Alex