segfault in pipewire when using ladspa plugin

[xobs]

I'm experiencing a segfault in pipewire when using the ladspa plugin:

(gdb) run
Starting program: /usr/bin/pipewire -c filter-chain.conf
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
[New Thread 0x7fffe9b9b6c0 (LWP 66372)]
[New Thread 0x7fffe922d6c0 (LWP 66373)]
2025-06-15T03:54:17.032Z | DEBUG |  df::tract | Loading model DeepFilterNet3_ll_onnx.tar.gz

Thread 3 "data-loop.0" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffe922d6c0 (LWP 66373)]
ladspa::ffi::connect_port (instance=0x0, port_num=0, data_location=0x7fffe88f10c0) at src/ffi.rs:236
236             let port = handle.descriptor.ports[port_num as usize];
(gdb) p handle
$2 = (*mut ladspa::ffi::Handle) 0x0
(gdb) list
231                                port_num: c_ulong,
232                                data_location: *mut ladspa_h::Data) {
233         unsafe {
234             let handle: &mut Handle = mem::transmute(instance);
235
236             let port = handle.descriptor.ports[port_num as usize];
237
238             // Create appropriate pointers to port data. Mutable locations are wrapped in refcells.
239             let data = match port.desc {
240                 super::PortDescriptor::AudioInput => {
(gdb) bt
#0  ladspa::ffi::connect_port (instance=0x0, port_num=0, data_location=0x7fffe88f10c0) at src/ffi.rs:236
#1  0x00007fffe8a01f71 in impl_process (object=0x5555555a7c98, in=<optimized out>, out=0x7fffe922c270, n_samples=1024)
    at ../spa/plugins/filter-graph/filter-graph.c:250
#2  0x00007ffff7c7c8b3 in spa_filter_graph_process (object=<optimized out>, in=0x7fffe922c670, out=0x7fffe922c270, n_samples=1024)
    at ../spa/include/spa/filter-graph/filter-graph.h:137
#3  playback_process (d=0x5555555babb0) at ../src/modules/module-filter-chain.c:932
#4  0x00007ffff7f4d619 in call_process (impl=0x55555564c280) at ../src/pipewire/stream.c:450
#5  call_process (impl=0x55555564c280) at ../src/pipewire/stream.c:443
#6  impl_node_process_output (object=0x55555564c280) at ../src/pipewire/stream.c:1127
#7  0x00007fffe8944243 in spa_node_process_fast (object=<optimized out>) at ../spa/include/spa/node/node.h:756
#8  impl_node_process (object=0x55555567ac78) at ../spa/plugins/audioconvert/audioadapter.c:1817
#9  0x00007ffff7f28097 in spa_node_process_fast (object=<optimized out>) at ../spa/include/spa/node/node.h:756
#10 process_node.isra.0 (data=data@entry=0x5555556a4750, nsec=nsec@entry=17845689604530) at ../src/pipewire/impl-node.c:1498
#11 0x00007ffff7f28526 in node_on_fd_events (source=<optimized out>) at ../src/pipewire/impl-node.c:1575
#12 0x00007ffff7c9e7c6 in loop_iterate (object=<optimized out>, timeout=<optimized out>) at ../spa/plugins/support/loop.c:726
#13 0x00007ffff7ef7741 in do_loop (user_data=0x5555555658b0) at ../src/pipewire/data-loop.c:67
#14 0x00007ffff7d5c1d4 in start_thread (arg=<optimized out>) at pthread_create.c:448
#15 0x00007ffff7ddecec in __GI___clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78
(gdb) 

You can see that it's entered the plugin due to the log message getting printed, but somehow the instance being returned is NULL.

[jacksongoode]

LADPSA is quite an old plugin hosting format. Are there better ways of hooking this up with Pipewire to avoid the LADPSA interface?

[github-actions[bot]]

This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 7 days.

[xobs]

I'm not sure -- I'm not familiar with the way filters are arranged under Linux.

At any rate, this patch solves the immediate problem of the segfault.

If the author @Rikorose doesn't want to solve this segfault and intends to rewrite it to use a different adapter mechanism, or if this repository is abandoned, then I'll let the bot close the issue and look for another solution.