linux-kernel - Re: [PATCH v2] s390/vfio_ap: fix memory leak in vfio

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Date:   Tue, 21 Mar 2023 08:47:44 -0400
From:   Anthony Krowiak <akrowiak@...ux.ibm.com>
To:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     borntraeger@...ibm.com, pasic@...ux.vnet.ibm.com,
        jjherne@...ux.ibm.com, frankja@...ux.ibm.com, david@...hat.com,
        imbrenda@...ux.ibm.com, hca@...ux.ibm.com
Subject: Re: [PATCH v2] s390/vfio_ap: fix memory leak in vfio_ap device driver

PING!

On 3/20/23 11:04 AM, Tony Krowiak wrote:
> The device release callback function invoked to release the matrix device
> uses the dev_get_drvdata(device *dev) function to retrieve the
> pointer to the vfio_matrix_dev object in order to free its storage. The
> problem is, this object is not stored as drvdata with the device; since the
> kfree function will accept a NULL pointer, the memory for the
> vfio_matrix_dev object is never freed.
>
> Since the device being released is contained within the vfio_matrix_dev
> object, the container_of macro will be used to retrieve its pointer.
>
> Fixes: 1fde573413b5 ("s390: vfio-ap: base implementation of VFIO AP device driver")
> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
> Reviewed-by: Harald Freudenberger <freude@...ux.ibm.com>
> ---
>   drivers/s390/crypto/vfio_ap_drv.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
> index 997b524bdd2b..a48c6938ae68 100644
> --- a/drivers/s390/crypto/vfio_ap_drv.c
> +++ b/drivers/s390/crypto/vfio_ap_drv.c
> @@ -54,8 +54,9 @@ static struct ap_driver vfio_ap_drv = {
>   
>   static void vfio_ap_matrix_dev_release(struct device *dev)
>   {
> -	struct ap_matrix_dev *matrix_dev = dev_get_drvdata(dev);
> +	struct ap_matrix_dev *matrix_dev;
>   
> +	matrix_dev = container_of(dev, struct ap_matrix_dev, device);
>   	kfree(matrix_dev);
>   }
>