[PATCH] s390/vfio-ap: lock mdev object when handling mdev remove request

Anthony Krowiak
2025-02-21T15:32:44Z

The vfio_ap_mdev_request function in drivers/s390/crypto/vfio_ap_ops.c
accesses fields of an ap_matrix_mdev object without ensuring that the
object is accessed by only one thread at a time. This patch adds the lock
necessary to secure access to the ap_matrix_mdev object.

Fixes: 2e3d8d71e285 ("s390/vfio-ap: wire in the vfio_device_ops request callback")
Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
Cc: <stable@vger.kernel.org>
---
drivers/s390/crypto/vfio_ap_ops.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index a52c2690933f..a2784d3357d9 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -2045,6 +2045,7 @@ static void vfio_ap_mdev_request(struct vfio_device *vdev, unsigned int count)
struct ap_matrix_mdev *matrix_mdev;

matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
+ mutex_lock(&matrix_dev->mdevs_lock);

if (matrix_mdev->req_trigger) {
if (!(count % 10))
@@ -2057,6 +2058,8 @@ static void vfio_ap_mdev_request(struct vfio_device *vdev, unsigned int count)
dev_notice(dev,
"No device request registered, blocked until released by user\n");
}
+
+ mutex_unlock(&matrix_dev->mdevs_lock);
}

static int vfio_ap_mdev_get_device_info(unsigned long arg)
--
2.47.1