UnigramDev/Unigram/crash-vlc-dangling-audio-device • 3bd0033 • 1 files, +9/-1
Fix crash when the default audio device changes during playback

OnDefaultAudioRenderDeviceChanged handed libvlc a pointer to a string that
had already been destroyed:

Set(libvlc_audio_output_set, winrt::to_string(args.Id()).c_str());

Set forwards its arguments into a lambda that Write queues for the player's
worker thread, and captures them by value — which for a const char* copies the
pointer, not the characters. The temporary std::string returned by to_string
dies at the end of that statement, so by the time the work item is dequeued
libvlc reads freed memory.

The crash lands in strcmp, called from module_exists by
libvlc_audio_output_set as it compares the device name against known module
names, which is exactly what reading a freed string looks like.

Own the string in the capture instead, matching the Write call sites that
already exist in this file.

This fires whenever the system's default audio render device changes while a
player is alive — headphones plugged in or removed, a Bluetooth device
connecting, a call starting — which is why it is common enough to matter
despite needing a device change to trigger. Reported by crash telemetry on
12.8.1; the code is unchanged on develop.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

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