[PATCH v6 6/6] vhost: Add check for inherit_owner status

[Cindy Lu]

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

Signed-off-by: Cindy Lu <l...@redhat.com>
---
 drivers/vhost/vhost.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 45d8f5c5bca9..26da561c6685 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1017,6 +1017,13 @@ long vhost_worker_ioctl(struct vhost_dev *dev, unsigned 
int ioctl,
        switch (ioctl) {
        /* dev worker ioctls */
        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 (!dev->inherit_owner)
+                       return -EFAULT;
                ret = vhost_new_worker(dev, &state);
                if (!ret && copy_to_user(argp, &state, sizeof(state)))
                        ret = -EFAULT;
-- 
2.45.0