ffa_composite_mem_region
sizeof(struct ffa_composite_mem_region) +
struct ffa_composite_mem_region *reg;
if (check_add_overflow(offset, sizeof(struct ffa_composite_mem_region), &checked_offset)) {
struct ffa_composite_mem_region *reg;
struct ffa_composite_mem_region *composite;
(offsetof(struct ffa_composite_mem_region, constituents[x]))