Regarding the troubleshooting with gdb, the idea is to print all chunks of memory if you didn't get the `qm_status` log messages.
The wiki has some gdb scripts at:
* https://www.kamailio.org/wiki/tutorials/troubleshooting/memory#using_gdb
But they are for pkg as they use `mem_block` and the issue here seems to be in shm, so you have to use `shm_block` instead of `mem_block`.
The target is to find the fragment before the one that has the beginning overwritten, listed in the log message:
``` Mar 9 10:33:49 kamserv /usr/local/sbin/kamailio[2945]: : <core> [mem/q_malloc.c:140]: qm_debug_frag(): BUG: qm_*: fragm. 0x7f064ea52480 (address 0x7f064ea524b0) beginning overwritten(646e756f622d6575)! ```
Probably you can adjust the gdb scripts in order to print first only the addresses for fragments, then print the content of the fragment before the one overwritten.