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From: Jason Wang <jasowang@redhat.com>
To: mst@redhat.com, jasowang@redhat.com, kvm@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH net 1/4] vhost: make sure used idx is seen before log in vhost_add_used_n()
Date: Mon, 10 Dec 2018 17:44:51 +0800	[thread overview]
Message-ID: <20181210094454.21144-2-jasowang@redhat.com> (raw)
In-Reply-To: <20181210094454.21144-1-jasowang@redhat.com>

We miss a write barrier that guarantees used idx is updated and seen
before log. This will let userspace sync and copy used ring before
used idx is update. Fix this by adding a barrier before log_write().

Fixes: 8dd014adfea6f ("vhost-net: mergeable buffers support")
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vhost/vhost.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 6b98d8e3a5bf..5915f240275a 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2220,6 +2220,8 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
 		return -EFAULT;
 	}
 	if (unlikely(vq->log_used)) {
+		/* Make sure used idx is seen before log. */
+		smp_wmb();
 		/* Log used index update. */
 		log_write(vq->log_base,
 			  vq->log_addr + offsetof(struct vring_used, idx),
-- 
2.17.1


  reply	other threads:[~2018-12-10  9:45 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-10  9:44 [PATCH net 0/4] Fix various issue of vhost Jason Wang
2018-12-10  9:44 ` Jason Wang [this message]
2018-12-10  9:44 ` [PATCH net 2/4] vhost_net: rework on the lock ordering for busy polling Jason Wang
2018-12-11  1:34   ` Michael S. Tsirkin
2018-12-11  3:06     ` Jason Wang
2018-12-11  4:04       ` Michael S. Tsirkin
2018-12-12  3:03         ` Jason Wang
2018-12-12  3:40           ` Michael S. Tsirkin
2018-12-10  9:44 ` [PATCH net 3/4] Revert "net: vhost: lock the vqs one by one" Jason Wang
2018-12-10  9:44 ` [PATCH net 4/4] vhost: log dirty page correctly Jason Wang
2018-12-10 15:14   ` kbuild test robot
2018-12-11  1:30     ` Michael S. Tsirkin
2018-12-19 17:29   ` kbuild test robot
2018-12-10 19:47 ` [PATCH net 0/4] Fix various issue of vhost David Miller
2018-12-11  3:01   ` Jason Wang

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