[PATCH v8 7/8] vhost: Add check for inherit_owner status

Cindy Lu
2025-03-28T10:05:14Z

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 <lulu@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 ff930c2e5b78..fb0c7fb43f78 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1018,6 +1018,13 @@ 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