projects / thirdparty / kernel / stable-queue.git / blame
| Commit | Line | Data |
|---|---|---|
| c923e3ad GKH |
1 | From foo@baz Sat Jan 5 08:35:42 CET 2019 |
| 2 | From: Jason Wang <jasowang@redhat.com> | |
| 3 | Date: Thu, 13 Dec 2018 10:53:37 +0800 | |
| 4 | Subject: vhost: make sure used idx is seen before log in vhost_add_used_n() | |
| 5 | ||
| 6 | From: Jason Wang <jasowang@redhat.com> | |
| 7 | ||
| 8 | [ Upstream commit 841df922417eb82c835e93d4b93eb6a68c99d599 ] | |
| 9 | ||
| 10 | We miss a write barrier that guarantees used idx is updated and seen | |
| 11 | before log. This will let userspace sync and copy used ring before | |
| 12 | used idx is update. Fix this by adding a barrier before log_write(). | |
| 13 | ||
| 14 | Fixes: 8dd014adfea6f ("vhost-net: mergeable buffers support") | |
| 15 | Acked-by: Michael S. Tsirkin <mst@redhat.com> | |
| 16 | Signed-off-by: Jason Wang <jasowang@redhat.com> | |
| 17 | Signed-off-by: David S. Miller <davem@davemloft.net> | |
| 18 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
| 19 | --- | |
| 20 | drivers/vhost/vhost.c | 2 ++ | |
| 21 | 1 file changed, 2 insertions(+) | |
| 22 | ||
| 23 | --- a/drivers/vhost/vhost.c | |
| 24 | +++ b/drivers/vhost/vhost.c | |
| 25 | @@ -1409,6 +1409,8 @@ int vhost_add_used_n(struct vhost_virtqu | |
| 26 | return -EFAULT; | |
| 27 | } | |
| 28 | if (unlikely(vq->log_used)) { | |
| 29 | + /* Make sure used idx is seen before log. */ | |
| 30 | + smp_wmb(); | |
| 31 | /* Log used index update. */ | |
| 32 | log_write(vq->log_base, | |
| 33 | vq->log_addr + offsetof(struct vring_used, idx), |