linux-kernel - [PATCH v6 6/6] vhost: Add check for inherit

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Message-ID: <20250223154042.556001-7-lulu@redhat.com>
Date: Sun, 23 Feb 2025 23:36:21 +0800
From: Cindy Lu <lulu@...hat.com>
To: lulu@...hat.com,
	jasowang@...hat.com,
	mst@...hat.com,
	michael.christie@...cle.com,
	sgarzare@...hat.com,
	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org,
	netdev@...r.kernel.org
Subject: [PATCH v6 6/6] vhost: Add check for inherit_owner status

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@...hat.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