lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20210621155714.1198545-2-akrowiak@linux.ibm.com>
Date:   Mon, 21 Jun 2021 11:57:13 -0400
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     borntraeger@...ibm.com, cohuck@...hat.com,
        pasic@...ux.vnet.ibm.com, jjherne@...ux.ibm.com, jgg@...dia.com,
        alex.williamson@...hat.com, kwankhede@...dia.com,
        frankja@...ux.ibm.com, david@...hat.com, imbrenda@...ux.ibm.com,
        hca@...ux.ibm.com
Subject: [PATCH v6 1/2] s390/vfio-ap: clean up mdev resources when remove callback invoked

The mdev remove callback for the vfio_ap device driver bails out with
-EBUSY if the mdev is in use by a KVM guest (i.e., the KVM pointer in the
struct ap_matrix_mdev is not NULL). The intended purpose was
to prevent the mdev from being removed while in use. There are two
problems with this scenario:

1. Returning a non-zero return code from the remove callback does not
   prevent the removal of the mdev.

2. The KVM pointer in the struct ap_matrix_mdev will always be NULL because
   the remove callback will not get invoked until the mdev fd is closed.
   When the mdev fd is closed, the mdev release callback is invoked and
   clears the KVM pointer from the struct ap_matrix_mdev.

Let's go ahead and remove the check for KVM in the remove callback and
allow the cleanup of mdev resources to proceed.

Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
Cc: stable@...r.kernel.org
---
 drivers/s390/crypto/vfio_ap_ops.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index b2c7e10dfdcd..122c85c22469 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -366,16 +366,6 @@ static int vfio_ap_mdev_remove(struct mdev_device *mdev)
 	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 
 	mutex_lock(&matrix_dev->lock);
-
-	/*
-	 * If the KVM pointer is in flux or the guest is running, disallow
-	 * un-assignment of control domain.
-	 */
-	if (matrix_mdev->kvm_busy || matrix_mdev->kvm) {
-		mutex_unlock(&matrix_dev->lock);
-		return -EBUSY;
-	}
-
 	vfio_ap_mdev_reset_queues(mdev);
 	list_del(&matrix_mdev->node);
 	kfree(matrix_mdev);
-- 
2.30.2

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ