} else if (((smpi_comm_rank(comm)==root) && (sendtype == MPI_DATATYPE_NULL))
|| ((recvbuf !=MPI_IN_PLACE) && (recvtype == MPI_DATATYPE_NULL))) {
retval = MPI_ERR_TYPE;
- } else {
+ } else if ((sendbuf == recvbuf) ||
+ ((smpi_comm_rank(comm)==root) && sendcount>0 && (sendbuf == NULL))){
+ retval = MPI_ERR_BUFFER;
+ }else {
if (recvbuf == MPI_IN_PLACE) {
recvtype=sendtype;