Bug 1425561

+++ This bug was initially created as a clone of Bug #1398387 +++
 - a clone requested by Arjun Shankar

Description of problem:
When debugging with gdb and using tab completion, gdb can crash with SIGSEGV.

I have tracked it down a bit with gdb itself (running gdb in gdb)

Version-Release number of selected component (if applicable):
gdb-7.12-29.fc25.x86_64

How reproducible:
I can, for example, reproduce it with the tool "pidof":

Steps to Reproduce:
1. sudo dnf install systemd-debuginfo pcre-debuginfo (with debug repos enabled)
2. gdb pidof
3. on gdb shell:
 * break main
 * run
4. when it breaks:
 * enter "p si" and press <tab>

Actual results:
gdb crashes with sigsegv

Expected results:
do not crash

Additional info:
If I uninstall the debuginfo packages installed above, it does not crash. I also had to deinstall libselinux-debuginfo, which also caused the problem

To figure out the file which causes the crash, I ran gdb in gdb:

1. gdb --args gdb pidof
2. on gdb shell
 * run
3. now on inner gbb shell
 * break main
 * run
4. when it breaks:
 * enter "p si" and press <tab>
5. SIGSEGV catched by outer gdb,
 * frame 2
 * p objfile.original_name

The crash depends on the pattern entered for the print command, some do not crash, some do crash. For me it is crashing with "si" and "so", but not for example for "sx".

crash dump is here:
https://retrace.fedoraproject.org/faf/reports/1372720/

--- Additional comment from Nicholas Miell on 2017-01-09 21:23:27 CET ---

I'm also seeing a crash in add_symtab_completions when attempting to tab complete xcb_ symbols.

--- Additional comment from Jan Kratochvil on 2017-01-09 22:10:27 CET ---

e11c72c7e4879894b9711b5c0b8247c20c6050f6 is the first bad commit
commit e11c72c7e4879894b9711b5c0b8247c20c6050f6
Author: Gary Benson <gbenson>
Date:   Sat Jan 31 14:48:29 2015 -0800
    Build list of completions as symbol tables are expanded.

--- Additional comment from Gary Benson on 2017-02-01 18:30:31 CET ---

This seems really sensitive to what debuginfo you have installed.  I finally reproduced this by:

  1. Install F25
  2. dnf debuginfo-install systemd-debuginfo pcre-debuginfo
  3. dnf update gdb # to gdb-7.12.1-41.fc25.x86_64
  4. dnf debuginfo-install procps-ng-3.3.10-11.fc24.x86_64

Interestingly the final debuginfo-install downgraded pcre-debuginfo and systemd-debuginfo.  The final list of debuginfo packages I have is:

  gcc-base-debuginfo-6.2.1-2.fc25.x86_64
  gcc-debuginfo-6.2.1-2.fc25.x86_64
  glibc-debuginfo-2.24-3.fc25.x86_64
  glibc-debuginfo-common-2.24-3.fc25.x86_64
  libcap-debuginfo-2.25-2.fc25.x86_64
  libgcrypt-debuginfo-1.6.6-1.fc25.x86_64
  libgpg-error-debuginfo-1.24-1.fc25.x86_64
  libselinux-debuginfo-2.5-12.fc25.x86_64
  libsepol-debuginfo-2.5-10.fc25.x86_64
  lz4-debuginfo-r131-2.fc24.x86_64
  ncurses-debuginfo-6.0-6.20160709.fc25.x86_64
  pcre-debuginfo-8.39-6.fc25.x86_64
  procps-ng-debuginfo-3.3.10-11.fc24.x86_64
  systemd-debuginfo-231-10.fc25.x86_64
  xz-debuginfo-5.2.2-2.fc24.x86_64

--- Additional comment from Gary Benson on 2017-02-09 16:40:37 CET ---

Fix committed upstream:
https://sourceware.org/ml/gdb-patches/2017-02/msg00226.html