char *speex_header_to_packet_fxd(SpeexHeader *header, int *size,SpeexHeader* alloc){
   SpeexHeader *le_header;
   le_header = alloc;//(SpeexHeader*)speex_alloc(sizeof(SpeexHeader));
   //......
}

SpeexHeader alloc;//<-- allocated without maloc
speex_header_to_packet_fxd(&header,size,&alloc);