instdir/program/python.bin SIGSEGV on Jenkins lo_tb_master_linux, lo_tb_master_linux_dbg

[Stephan Bergmann]

Recently, some (but not all) of the 
<https://ci.libreoffice.org/job/lo_tb_master_linux/> and 
<https://ci.libreoffice.org/job/lo_tb_master_linux_dbg/> builds started 
to fail with SIGSEGV in instdir/program/python.bin as run during the 
build.  One example is 
<https://ci.libreoffice.org/job/lo_tb_master_linux/43342/>

> /bin/sh: line 1: 24274 Segmentation fault      (core dumped) LD_LIBRARY_PATH=${LD_LIBRARY_PATH:+$LD_LIBRARY_PATH:}"$I/program:$I/program" PYTHONHOME="$I/program/python-core-3.8.4" PYTHONPATH="${PYPATH:+$PYPATH:}$I/program/python-core-3.8.4/lib:$I/program/python-core-3.8.4/lib/lib-dynload" $I/program/python.bin $S/writerfilter/source/ooxml/factoryimpl_ns.py $W/CustomTarget/writerfilter/source/ooxml/model_preprocessed.xml $W/CustomTarget/writerfilter/source/ooxml/OOXMLFactory_wml.cxx > /home/tdf/lode/jenkins/workspace/lo_tb_master_linux/workdir/CustomTarget/writerfilter/source/ooxml/OOXMLFactory_wml.cxx
> /home/tdf/lode/jenkins/workspace/lo_tb_master_linux/writerfilter/CustomTarget_source.mk:98: recipe for target '/home/tdf/lode/jenkins/workspace/lo_tb_master_linux/workdir/CustomTarget/writerfilter/source/ooxml/OOXMLFactory_wml.cxx' failed
> make[1]: *** [/home/tdf/lode/jenkins/workspace/lo_tb_master_linux/workdir/CustomTarget/writerfilter/source/ooxml/OOXMLFactory_wml.cxx] Error 139
> make[1]: *** Deleting file '/home/tdf/lode/jenkins/workspace/lo_tb_master_linux/workdir/CustomTarget/writerfilter/source/ooxml/OOXMLFactory_wml.cxx'

where I think I captured the right (but unfortunately unhelpful) core 
file on tb75:

> [tdf at lilith ~]$ cd lode/jenkins/workspace/lo_tb_master_linux
> [tdf at lilith lo_tb_master_linux]$ ls -l core.24274
> -rw-------. 1 tdf users 4.2M Dec  4 11:54 core.24274
> [tdf at lilith lo_tb_master_linux]$ file core.24274
> core.24274: ELF 64-bit LSB core file x86-64, version 1 (SYSV), SVR4-style, from '/home/tdf/lode/jenkins/workspace/lo_tb_master_linux/instdir/program/python.bin', real uid: 10037, effective uid: 10037, real gid: 100, effective gid: 100, execfn: '/home/tdf/lode/jenkins/workspace/lo_tb_master_linux/instdir/program/python.bin', platform: 'x86_64'
> [tdf at lilith lo_tb_master_linux]$ gdb instdir/program/python.bin core.24274
> GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-119.el7
> Copyright (C) 2013 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "x86_64-redhat-linux-gnu".
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>...
> Reading symbols from /home/tdf/lode/jenkins/workspace/lo_tb_master_linux/instdir/program/python.bin...done.
> [New LWP 24274]
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib64/libthread_db.so.1".
> Core was generated by `/home/tdf/lode/jenkins/workspace/lo_tb_master_linux/instdir/program/python.bin'.
> Program terminated with signal 11, Segmentation fault.
> #0  0x0000000000000ae0 in ?? ()
> warning: File "/home/tdf/lode/jenkins/workspace/lo_tb_master_linux/instdir/program/python.bin-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load:/usr/bin/mono-gdb.py:/home/tdf/lode/jenkins/workspace/lo_gerrit/:/home/tdf/lode/opt_private/gcc-7.3.0/".
> To enable execution of this file add
> 	add-auto-load-safe-path /home/tdf/lode/jenkins/workspace/lo_tb_master_linux/instdir/program/python.bin-gdb.py
> line to your configuration file "/home/tdf/.gdbinit".
> To completely disable this security protection add
> 	set auto-load safe-path /
> line to your configuration file "/home/tdf/.gdbinit".
> For more information about this security protection see the
> "Auto-loading safe path" section in the GDB manual.  E.g., run from the shell:
> 	info "(gdb)Auto-loading safe path"
> Missing separate debuginfos, use: debuginfo-install glibc-2.17-307.el7.1.x86_64
> (gdb) t a a bt
> 
> Thread 1 (Thread 0x2af1d2787a40 (LWP 24274)):
> #0  0x0000000000000ae0 in ?? ()
> #1  0x00002af1d275307a in _dl_fini () from /lib64/ld-linux-x86-64.so.2
> #2  0x00002af1d3aa8ce9 in __run_exit_handlers () from /lib64/libc.so.6
> #3  0x00002af1d3aa8d37 in exit () from /lib64/libc.so.6
> #4  0x00002af1d3a9155c in __libc_start_main () from /lib64/libc.so.6
> #5  0x000000000040068e in _start ()
> (gdb) q
> [tdf at lilith lo_tb_master_linux]$ 

(Those Jenkins builds had started to fail apparently systematically with 
such instdir/program/python.bin SIGSEGV, but which then appeared to stop 
at least for the moment with admin_slave_cleaning, as discussed in the 
comments starting at 
<https://gerrit.libreoffice.org/c/core/+/106791/4#message-1702fc4900a2ca6db5720313481697dac1e9f37d> 
"Enable Python Py_DEBUG setting when built with --enable-dbgutil on Linux".)

If anybody has an idea what's going wrong there...