plugdata intermittently crashes with SIGSEGV while creating/editing object boxes.

[codecollider]

Description

plugdata intermittently crashes with SIGSEGV while creating/editing object boxes.

I have now reproduced this twice in the same patch:

1. while creating a [+ 1] object
2. while creating a [saw ...] object

It is not deterministic, but both crashes occurred while creating an object box.

On the second crash, plugdata was launched from a terminal. The final output immediately before the crash was:

JUCE Assertion failure in juce_WeakReference.h:170

System

• Ubuntu 24.04 LTS
• GNOME
• x86_64
• plugdata 0.9.32+git.0.49aa12ba-1
• Installation: OBS package from home:plugdata (Ubuntu 24.04)
• standalone
• ALSA backend via PipeWire

Crash analysis

Ubuntu Apport captured core dumps for both crashes.

Both terminate with:

SIGSEGV

and both crash in the main thread.

The installed /usr/bin/plugdata is stripped, so GDB cannot show
function names. However, after accounting for ASLR, both crashes
have exactly the same top three stack-frame offsets relative to
_start:

frame       crash 1          crash 2
#0          +0x174b91b       +0x174b91b
#1          +0x7cc2          +0x7cc2
#2          +0x2c229         +0x2c229

So these appear to be the same crash path.

For the second crash GDB shows:

=> mov 0x90(%r13),%r12

with:

r13 = 0x0

so the SIGSEGV is caused by dereferencing a null pointer
(at offset 0x90).

The terminal assertion immediately before this crash was:

JUCE Assertion failure in juce_WeakReference.h:170

Binary Build ID:

018015226978c7371c40d4d2258de4530d6490b6

I can provide the complete GDB output and/or test a debug build if useful.

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I used ChatGPT to help interpret the GDB output and draft this report; all commands and crash data shown above were obtained directly on my system.