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s390/vfio-ap: Fix required lock not held during update of ap_matrix_mdev object

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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: eeb386aeb5 ("s390/vfio-ap: handle config changed and scan complete notification")
Cc: stable@vger.kernel.org
Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
This commit is contained in:
Anthony Krowiak 2026-08-12 16:02:35 -04:00 committed by Christian Borntraeger
parent 7fa61c2985
commit 5883528250
1 changed files with 8 additions and 0 deletions
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8
drivers/s390/crypto/vfio_ap_ops.c
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@ -2772,12 +2772,20 @@ static void vfio_ap_mdev_cfg_add(unsigned long *apm_add, unsigned long *aqm_add,
* called.
*/
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);
}
}