[PATCH v2] s390/vfio-ap: Fix module unload memory leak of matrix_dev

["Jason J. Herne" <jjherne@linux.ibm.com>]

vfio_ap_matrix_dev_release is shadowing the global matrix_dev with a NULL
pointer. Driver data for the matrix device is never set and so
dev_get_drvdata() always returns NULL. When release is called we end up
not freeing matrix_dev. The fix is to remove the shadow variable and get
the correct pointer from the device using container_of. We'll also NULL
the global to prevent any future use.

Signed-off-by: Jason J. Herne <jjherne@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_drv.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index 7dc72cb718b0..40e66cb363d1 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -82,9 +82,8 @@ static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
 
 static void vfio_ap_matrix_dev_release(struct device *dev)
 {
-	struct ap_matrix_dev *matrix_dev = dev_get_drvdata(dev);
-
-	kfree(matrix_dev);
+	kfree(container_of(dev, struct ap_matrix_dev, device));
+	matrix_dev = NULL;
 }
 
 static int matrix_bus_match(struct device *dev, struct device_driver *drv)
-- 
2.21.1