11(12454) : <core> [mem/q_malloc.c:149]: qm_debug_frag(): BUG: qm_*: fragm. 0x7f9e8fcb2448 (address 0x7f9e8fcb2478) end overwritten(c0c0c000, abcdefed)!
13(12456) CRITICAL: <core> [pass_fd.c:293]: receive_fd(): EOF on 20
 0(12443) ALERT: <core> [main.c:784]: handle_sigs(): child process 12454 exited by a signal 6
 0(12443) ALERT: <core> [main.c:787]: handle_sigs(): core was generated
 0(12443) INFO: <core> [main.c:799]: handle_sigs(): terminating due to SIGCHLD
13(12456) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
12(12455) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
 9(12452) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
10(12453) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
 8(12451) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
 4(12447) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
 3(12446) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
 7(12450) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
 6(12449) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
 5(12448) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
 2(12445) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
 1(12444) INFO: <core> [main.c:850]: sig_usr(): signal 15 received
 0(12443) INFO: <core> [sctp_core.c:48]: sctp_core_destroy(): SCTP API not initialized



using kamailio 4.2
with modified tcp_read.c and tcp_main.c files for buffer manipulation both files attached

gdb output

Reading symbols from /usr/local/sbin/kamailio...done.

warning: exec file is newer than core file.
[New LWP 15502]

warning: Error reading shared library list entry at 0x79e8c789480056e4

warning: Error reading shared library list entry at 0x482a50b70fd8458b
Core was generated by `/usr/local/sbin/kamailio -f /usr/local/etc/kamailio/kamailio.cfg -P /var/run/ka'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x000000000061f73d in _shm_resize (p=0x61f729 <_shm_resize+541>, s=32767, file=0x3f <error: Cannot access memory at address 0x3f>, func=0x0, line=-1433800800)
    at mem/shm_mem.c:111
111            DBG("WARNING:vqm_resize: resize(0) called\n");