GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-110.el7
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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This GDB was configured as "x86_64-redhat-linux-gnu".
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<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/local/libexec/mupdate...done.
[New LWP 20804]
[New LWP 20803]
[New LWP 20801]
[New LWP 20800]
[New LWP 20799]
[New LWP 20802]
[New LWP 20798]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Core was generated by `mupdate -m -C /etc/imapd_mu.conf'.
Program terminated with signal 11, Segmentation fault.
#0  BN_clear_free (a=0x6120646e6966206f) at bn_lib.c:234
234	    if (a->d != NULL) {
(gdb) 
Thread 7 (Thread 0x7f58bbaf08c0 (LWP 20798)):
#0  0x00007f58b6716a2d in accept () at ../sysdeps/unix/syscall-template.S:81
#1  0x000000000040a232 in main (argc=4, argv=0x7ffd75303d68, envp=0x7ffd75303d90) at master/service-thread.c:268

Thread 6 (Thread 0x7f58b22d0700 (LWP 20802)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x0000000000405cd4 in thread_main (rock=0x0) at imap/mupdate.c:1142
#2  0x00007f58b670fdd5 in start_thread (arg=0x7f58b22d0700) at pthread_create.c:308
#3  0x00007f58b6184b3d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 5 (Thread 0x7f58b3ad3700 (LWP 20799)):
#0  0x00007f58b6716a2d in accept () at ../sysdeps/unix/syscall-template.S:81
#1  0x00000000004098fa in mupdate_placebo_kick_start (rock=0x0) at imap/mupdate-slave.c:351
#2  0x00007f58b670fdd5 in start_thread (arg=0x7f58b3ad3700) at pthread_create.c:308
#3  0x00007f58b6184b3d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 4 (Thread 0x7f58b32d2700 (LWP 20800)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x0000000000405cd4 in thread_main (rock=0x0) at imap/mupdate.c:1142
#2  0x00007f58b670fdd5 in start_thread (arg=0x7f58b32d2700) at pthread_create.c:308
#3  0x00007f58b6184b3d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 3 (Thread 0x7f58b2ad1700 (LWP 20801)):
#0  0x00007f58b617bcd9 in __pselect (nfds=15, readfds=0x7f58b2ad0bf0, writefds=0x0, exceptfds=0x0, timeout=<optimized out>, sigmask=<optimized out>)
    at ../sysdeps/unix/sysv/linux/pselect.c:77
#1  0x00007f58b951cfc2 in signals_select (nfds=15, rfds=0x7f58b2ad0bf0, wfds=0x0, efds=0x0, tout=0x7f58b2ad0be0) at lib/signals.c:257
#2  0x00007f58b951b483 in prot_select (readstreams=0x7f58a40008c0, extra_read_fd=10, out=0x7f58b2ad0d28, extra_read_flag=0x7f58b2ad0cfc, timeout=0x7f58b2ad0be0) at lib/prot.c:1578
#3  0x0000000000405e6e in thread_main (rock=0x0) at imap/mupdate.c:1199
#4  0x00007f58b670fdd5 in start_thread (arg=0x7f58b2ad1700) at pthread_create.c:308
#5  0x00007f58b6184b3d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 2 (Thread 0x7f58b1acf700 (LWP 20803)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x0000000000405cd4 in thread_main (rock=0x0) at imap/mupdate.c:1142
#2  0x00007f58b670fdd5 in start_thread (arg=0x7f58b1acf700) at pthread_create.c:308
#3  0x00007f58b6184b3d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 1 (Thread 0x7f58b12ce700 (LWP 20804)):
#0  BN_clear_free (a=0x6120646e6966206f) at bn_lib.c:234
#1  0x00007f58b8a4eab5 in DH_free (r=0x7f58a41be720) at dh_lib.c:203
#2  0x00007f58b9842bef in tls_shutdown_serverengine () at imap/tls.c:1311
#3  0x0000000000404075 in conn_free (C=0x7f58a4113a10) at imap/mupdate.c:379
#4  0x00000000004062c0 in thread_main (rock=0x0) at imap/mupdate.c:1330
#5  0x00007f58b670fdd5 in start_thread (arg=0x7f58b12ce700) at pthread_create.c:308
#6  0x00007f58b6184b3d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113
(gdb) quit