MT crashes

[<don...@is...>]

I hoped to hear something back from my last post on this subject (Apr 30).
I don't have a small example, but I think I have a repeatable example.
It seems that fedora 24 saves a lot of context in addition to the core
dump, though it wasn't easy to find it all.  One of the files,
named "exploitable" says:
Likely crash reason: Jump to an invalid address
Exploitable rating (0-9 scale): 6

I suppose this is the same info as the fact that the program
ended with 
 " Segmentation fault (core dumped)

Another, core_backtrace:
{   "signal": 11
,   "executable": "/home/tmp1/ap5-2.49.93+MT%"
,   "stacktrace":
      [ {   "crash_thread": true
        ,   "frames":
              [ {   "address": 4854162
                ,   "build_id": "76df05a878e27f6ee7cc5ed39793f74585c42684"
                ,   "build_id_offset": 659858
                ,   "file_name": "/home/tmp1/ap5-2.49.93+MT% (deleted)"
                } ]
        }
      , {   "frames":
              [ {   "address": 140191862768419
                ,   "build_id": "7e7c0136995d74da5288c3f0a0e53dd72e53d7d4"
                ,   "build_id_offset": 1020707
                ,   "function_name": "__select"
                ,   "file_name": "/lib64/libc.so.6"
                }
              , {   "address": 5385773
                ,   "build_id": "76df05a878e27f6ee7cc5ed39793f74585c42684"
                ,   "build_id_offset": 1191469
                ,   "file_name": "/home/tmp1/ap5-2.49.93+MT% (deleted)"
                } ]
        }
      , {   "frames":
              [ {   "address": 140191865756134
                ,   "build_id": "a6b759a4fe570ed140d81151888da045a3db488e"
                ,   "build_id_offset": 68070
                ,   "function_name": "sigwait"
                ,   "file_name": "/lib64/libpthread.so.0"
                }
              , {   "address": 4736398
                ,   "build_id": "76df05a878e27f6ee7cc5ed39793f74585c42684"
                ,   "build_id_offset": 542094
                ,   "file_name": "/home/tmp1/ap5-2.49.93+MT% (deleted)"
                } ]
        }
      , {   "frames":
              [ {   "address": 140191865753581
                ,   "build_id": "a6b759a4fe570ed140d81151888da045a3db488e"
                ,   "build_id_offset": 65517
                ,   "function_name": "accept"
                ,   "file_name": "/lib64/libpthread.so.0"
                }
              , {   "address": 5455784
                ,   "build_id": "76df05a878e27f6ee7cc5ed39793f74585c42684"
                ,   "build_id_offset": 1261480
                ,   "file_name": "/home/tmp1/ap5-2.49.93+MT% (deleted)"
                } ]
        }
      , {   "frames":
              [ {   "address": 140191862768419
                ,   "build_id": "7e7c0136995d74da5288c3f0a0e53dd72e53d7d4"
                ,   "build_id_offset": 1020707
                ,   "function_name": "__select"
                ,   "file_name": "/lib64/libc.so.6"
                }
              , {   "address": 6292742
                ,   "build_id": "76df05a878e27f6ee7cc5ed39793f74585c42684"
                ,   "build_id_offset": 2098438
                ,   "file_name": "/home/tmp1/ap5-2.49.93+MT% (deleted)"
                } ]
        } ]
}


I'm hoping someone can give me advice on how to look for the problem,
or better, how to help some else who understands it all better than I
do to look for the problem.