vhost: fix the memory leak which will happen when memory_access_ok fails

We need to free newmem when vhost_set_memory() fails to complete.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/vhost.c

@@ -337,8 +337,10 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
 		return -EFAULT;
 	}
 
-	if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL)))
+	if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL))) {
+		kfree(newmem);
 		return -EFAULT;
+	}
 	oldmem = d->memory;
 	rcu_assign_pointer(d->memory, newmem);
 	synchronize_rcu();