ardour-5.12.0 assert failure: double free or corruption (out)

[Phelps Scofield]

[Impact]

 * Currently, this is the number one bug affecting Ardour users of Ubuntu (including Ubuntu Studio) per the Ardour team.

[Test Case]

 * Install Ardour in Ubuntu (or simply install Ubuntu Studio on a system)
 * Attempt to launch Ardour.
 * Test will fail if there is a crash without explanation or apport bug alert. Please note that failure does not occur on all systems.

 * Workaround: uninstall csladspa

[Regression Potential]

 * None.

[Other Info]

 * Per the Ardour team, this is currently their number one bug report. Only workaround is to remove csladspa which isn't ideal for Ubuntu Studio users expecting the distro to work "out of the box."
 * Working with the Ardour team keeps (and/or reestablishes) Ubuntu (and therefore Ubuntu Studio) as a recommended distro for audio production and use of their product. This bug is currently an hindrance to that effort.

Original bug:

After installing the Cadence program from KXStudio, Ardour presented this crash.

ProblemType: Crash
DistroRelease: Ubuntu 18.04
Package: ardour 1:5.12.0-3
ProcVersionSignature: Ubuntu 4.15.0-13.14-lowlatency 4.15.10
Uname: Linux 4.15.0-13-lowlatency x86_64
ApportVersion: 2.20.9-0ubuntu1
Architecture: amd64
AssertionMessage: double free or corruption (out)
CrashCounter: 1
CurrentDesktop: XFCE
Date: Wed Mar 28 16:41:23 2018
ExecutablePath: /usr/lib/ardour5/ardour-5.12.0
InstallationDate: Installed on 2018-03-17 (11 days ago)
InstallationMedia: Ubuntu-Studio 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180316)
ProcCmdline: /usr/lib/ardour5/ardour-5.12.0
Signal: 6
SourcePackage: ardour
StacktraceTop:
 __libc_message (action=action@entry=do_abort, fmt=fmt@entry=0x7f34f0b36b9a "%s\n") at ../sysdeps/posix/libc_fatal.c:181
 malloc_printerr (str=str@entry=0x7f34f0b38870 "double free or corruption (out)") at malloc.c:5350
 _int_free (have_lock=0, p=0x7ffd6c78cb90, av=0x7f34f0d6bc40 <main_arena>) at malloc.c:4278
 __GI___libc_free (mem=0x7ffd6c78cba0) at malloc.c:3124
 () at /usr/lib/ladspa/csladspa.so
Title: ardour-5.12.0 assert failure: double free or corruption (out)
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm audio cdrom dip lpadmin plugdev sambashare sudo

[Apport retracing service (apport)]

StacktraceTop:
 __libc_message (action=action@entry=do_abort, fmt=fmt@entry=0x7f34f0b36b9a "%s\n") at ../sysdeps/posix/libc_fatal.c:181
 malloc_printerr (str=str@entry=0x7f34f0b38870 "double free or corruption (out)") at malloc.c:5350
 _int_free (have_lock=0, p=0x7ffd6c78cb90, av=0x7f34f0d6bc40 <main_arena>) at malloc.c:4278
 __GI___libc_free (mem=0x7ffd6c78cba0) at malloc.c:3124
 CountCSD (csdnames=csdnames@entry=0x55fe6d1e6fa0) at ../frontends/csladspa/csladspa.cpp:451

[Colin Watson (cjwatson)]

I'm told this is fixed in Ubuntu 18.10 (via the split-out upstream package csladspa 6.11.1). I'm reasonably sure that cherry-picking https://github.com/csound/csladspa/commit/ecc7f131c5530ad517254dd5b24ba9b2742f69ab will do the job here.

[Erich Eickmeyer (eeickmeyer)]

Added SRU information for review.