In the vfio_ap_mdev_cfg_add function, the apm_add, aqm_add and adm_add fields of an ap_matrix_mdev object fields are modified while not holding the matrix_dev->mdevs_lock. This lock must be held while making these to guard against a race condition with another caller that may be concurrently modifying these fields or any of the fields in the matrix_mdev->matrix. Fixes: eeb386aeb5b7c ("s390/vfio-ap: handle config changed and scan complete notification") Cc: stable@vger.kernel.org Signed-off-by: Anthony Krowiak Reviewed-by: Matthew Rosato --- drivers/s390/crypto/vfio_ap_ops.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c index 5c14ded4fd8e..8a1ecb891504 100644 --- a/drivers/s390/crypto/vfio_ap_ops.c +++ b/drivers/s390/crypto/vfio_ap_ops.c @@ -2760,12 +2760,20 @@ static void vfio_ap_mdev_cfg_add(unsigned long *apm_add, unsigned long *aqm_add, vfio_ap_filter_apid_by_qtype(apm_add, aqm_add); list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) { + /* + * The mdevs_lock must be held in order to access fields + * within matrix_mdev + */ + mutex_lock(&matrix_dev->mdevs_lock); + bitmap_and(matrix_mdev->apm_add, matrix_mdev->matrix.apm, apm_add, AP_DEVICES); bitmap_and(matrix_mdev->aqm_add, matrix_mdev->matrix.aqm, aqm_add, AP_DOMAINS); bitmap_and(matrix_mdev->adm_add, matrix_mdev->matrix.adm, adm_add, AP_DEVICES); + + mutex_unlock(&matrix_dev->mdevs_lock); } } -- 2.53.0