[PATCH 5.4 12/85] vhost: Use vhost_get_used_size() in vhost_vring_set_addr()

[Greg Kroah-Hartman]

From: Greg Kurz <groug@xxxxxxxx>

commit 71878fa46c7e3b40fa7b3f1b6e4ba3f92f1ac359 upstream.

The open-coded computation of the used size doesn't take the event
into account when the VIRTIO_RING_F_EVENT_IDX feature is present.
Fix that by using vhost_get_used_size().

Fixes: 8ea8cf89e19a ("vhost: support event index")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kurz <groug@xxxxxxxx>
Link: https://lore.kernel.org/r/160171932300.284610.11846106312938909461.stgit@xxxxxxxxx
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/vhost/vhost.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1545,8 +1545,7 @@ static long vhost_vring_set_addr(struct
 		/* Also validate log access for used ring if enabled. */
 		if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
 			!log_access_ok(vq->log_base, a.log_guest_addr,
-				sizeof *vq->used +
-				vq->num * sizeof *vq->used->ring))
+				       vhost_get_used_size(vq, vq->num)))
 			return -EINVAL;
 	}