dgram_pair_read_inner(): Do not move buf pointer if it is NULL
@@ -745,6 +745,7 @@ static size_t dgram_pair_read_inner(struct bio_dgram_pair_st *b, uint8_t *buf, s
ring_buf_pop(&b->rbuf, src_len);
+ if (buf != NULL)
buf += src_len;
total_read += src_len;
sz -= src_len;
