[PATCH v4 8/8] vhost_scsi: Add check for inherit_owner status

[Cindy Lu <lulu@redhat.com>]

The vhost_scsi VHOST_NEW_WORKER requires the inherit_owner
setting to be true. So we need to implement a check for this.

Signed-off-by: Cindy Lu <lulu@redhat.com>
---
 drivers/vhost/scsi.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 718fa4e0b31e..0d63b6b5c852 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -2086,6 +2086,14 @@ vhost_scsi_ioctl(struct file *f,
 			return -EFAULT;
 		return vhost_scsi_set_features(vs, features);
 	case VHOST_NEW_WORKER:
+		/*
+		 * vhost_tasks will account for worker threads under the parent's
+		 * NPROC value but kthreads do not. To avoid userspace overflowing
+		 * the system with worker threads inherit_owner must be true.
+		 */
+		if (!vs->dev.inherit_owner)
+			return -EFAULT;
+		fallthrough;
 	case VHOST_FREE_WORKER:
 	case VHOST_ATTACH_VRING_WORKER:
 	case VHOST_GET_VRING_WORKER:
-- 
2.45.0