Re: [syzbot] [kvm?] [net?] [virt?] general protection fault in vhost_work_queue
From: Mike Christie <michael.christie@oracle.com>
Date: 2023-05-30 16:02:10
Also in:
kvm, lkml, virtualization
On 5/30/23 10:58 AM, Mike Christie wrote:
quoted hunk ↗ jump to hunk
On 5/30/23 8:44 AM, Stefano Garzarella wrote:quoted
From a first glance, it looks like an issue when we call vhost_work_queue(). @Mike, does that ring any bells since you recently looked at that code?I see the bug. needed to have set the dev->worker after setting worker->vtsk like below:diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index a92af08e7864..7bd95984a501 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c@@ -564,7 +564,6 @@ static int vhost_worker_create(struct vhost_dev *dev) if (!worker) return -ENOMEM; - dev->worker = worker; worker->kcov_handle = kcov_common_handle(); init_llist_head(&worker->work_list); snprintf(name, sizeof(name), "vhost-%d", current->pid);@@ -576,6 +575,7 @@ static int vhost_worker_create(struct vhost_dev *dev) } worker->vtsk = vtsk;
Shoot, oh wait, I think I needed a smp_wmb to always make sure worker->vtask is set before dev->worker or vhost_work_queue could still end up seeing dev->worker set before worker->vtsk right?
+ dev->worker = worker;> vhost_task_start(vtsk); return 0;