+/*
+ * Copy a request from userspace. If the provided 'req' is larger than the
+ * user buffer then the user buffer is zero extended into the 'req'. If 'req'
+ * is smaller than the user buffer then the uncopied bytes in the user buffer
+ * must be zero.
+ */
+static int uverbs_request(struct uverbs_attr_bundle *attrs, void *req,
+ size_t req_len)
+{
+ if (copy_from_user(req, attrs->ucore.inbuf,
+ min(attrs->ucore.inlen, req_len)))
+ return -EFAULT;
+
+ if (attrs->ucore.inlen < req_len) {
+ memset(req + attrs->ucore.inlen, 0,
+ req_len - attrs->ucore.inlen);
+ } else if (attrs->ucore.inlen > req_len) {
+ if (!ib_is_buffer_cleared(attrs->ucore.inbuf + req_len,
+ attrs->ucore.inlen - req_len))
+ return -EOPNOTSUPP;
+ }
+ return 0;
+}
+