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| author | Jason Wang <jasowang@redhat.com> | 2018-12-13 03:53:37 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-12-13 06:56:19 +0100 |
| commit | 841df922417eb82c835e93d4b93eb6a68c99d599 (patch) | |
| tree | 0286f8784c5eafeda7b38db9cc989780b34387cf | |
| parent | Merge branch '40GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/jkirshe... (diff) | |
| download | linux-841df922417eb82c835e93d4b93eb6a68c99d599.tar.xz linux-841df922417eb82c835e93d4b93eb6a68c99d599.zip | |
vhost: make sure used idx is seen before log in vhost_add_used_n()
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")
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/vhost/vhost.c | 2 |
1 files changed, 2 insertions, 0 deletions
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), |