Both leak detection and access checking require that the standard heap management routines in the shared library libc.so be used so that runtime checking can keep track of all the allocations and deallocations in the program. Many applications write their own memory management routines either on top of the malloc() or free() function or stand alone. When you use your own allocators (referred to as private allocators), runtime checking cannot automatically track them. Therefore, you do not learn of leak and memory access errors resulting from their improper use.
However, runtime checking provides an API for the use of private allocators. This API allows the private allocators the same treatment as the standard heap allocators. The API itself is provided in the header file rtc-api.h and is distributed as a part of Oracle Developer Studiosoftware. The man page rtc_api(3x) details the runtime checking API entry points.
Some minor differences might exist with runtime checking access error reporting when private allocators do not use the program heap. When a memory access error referring to a standard heap block occurs, the error report typically includes the location of the heap block allocation. When private allocators do not use the program heap, the error report might not include the allocation item.
Using the runtime checking API to track memory allocators in libumem is not required. Runtime checking interposes libumem heap management routines and redirects them to the corresponding libc functions.