The heap dumper currently trusts the glibc data structures (or its interpretation thereof). There is some cross-checking (and the test suite checks the heap dumper results against a list of known allocations). It would be preferable if there was a mode that performs more extensive data validation, recording for every 16 bytes of memory what its state is. Using bin links, it should be possible to double-check that all allocations and unallocated chunks have indeed been found.