luca@openldap.org writes:

Slapcat on a slapd instance using rwm overlay, aborts with: *** glibc detected *** free(): invalid pointer: 0x09ed06e3 ***

It's an invalid free() of (static EntryHeader eh).e_bv.bv_val at: ch_free (ch_malloc.c:139) hdb_tool_entry_close (back-hdb/tools.c:164) slapcat (slapcat.c:135) main (main.c:636) already freed (as (Entry *e)->e_bv.bv_val) at: ch_free (ch_malloc.c:139) entry_clean (entry.c:498) entry_free (entry.c:514) rwm_entry_release_rw (overlays/rwm.c:827) overlay_entry_release_ov (backover.c:421) over_entry_release_rw (backover.c:463) be_entry_release_rw (backend.c:867) slapcat (slapcat.c:117) main (main.c:636)

I needed to prepend include servers/slapd/schema/core.schema to your config.