Improper use of negative value.

If ret < 0 on account of the following assignment then it should not be further passed to constant_time_msb_s function as this function accepts parameter of type size_t .

ret = ossl_rsa_padding_check_PKCS1_type_2_TLS(
                        prsactx->libctx, out, outsize, tbuf, len,
                        prsactx->client_version, prsactx->alt_version);

CLA: trivial