s390/vfio-ap: fix memory leak in vfio_ap device driver

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2188088

commit 8f8cf76
Author: Tony Krowiak <akrowiak@linux.ibm.com>
Date:   Mon Mar 20 11:04:47 2023 -0400

    s390/vfio-ap: fix memory leak in vfio_ap device driver

    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: 1fde573 ("s390: vfio-ap: base implementation of VFIO AP device driver")
    Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
    Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
    Link: https://lore.kernel.org/r/20230320150447.34557-1-akrowiak@linux.ibm.com
    Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
    Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Author: Alex Williamson

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);
 }