vhost: fix error path in vhost_init_used()

We don't want side effects. If something fails, we rollback vq->is_le to
its previous value.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index ad2146a..236553e 100644 (file)
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1156,6 +1156,8 @@ int vhost_init_used(struct vhost_virtqueue *vq)
 {
        __virtio16 last_used_idx;
        int r;
+       bool is_le = vq->is_le;
+
        if (!vq->private_data) {
                vq->is_le = virtio_legacy_is_little_endian();
                return 0;
@@ -1165,15 +1167,20 @@ int vhost_init_used(struct vhost_virtqueue *vq)
 
        r = vhost_update_used_flags(vq);
        if (r)
-               return r;
+               goto err;
        vq->signalled_used_valid = false;
-       if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx))
-               return -EFAULT;
+       if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
+               r = -EFAULT;
+               goto err;
+       }
        r = __get_user(last_used_idx, &vq->used->idx);
        if (r)
-               return r;
+               goto err;
        vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
        return 0;
+err:
+       vq->is_le = is_le;
+       return r;
 }
 EXPORT_SYMBOL_GPL(vhost_init_used);