Executive brief
The Linux kernel's audio subsystem (ASoC) has a synchronization bug in the compress stream handling code that can cause the kernel to panic when certain configuration options are enabled. When an application opens a compressed audio stream (DPCM), internal functions are called without proper mutex protection, triggering panic conditions in systems configured to fail safely on warnings. This affects audio playback and recording on affected systems.
Technical details
This is a synchronization/locking bug in the ASoC (ALSA System on Chip) audio compression driver code. The vulnerability exists because functions like `dpcm_be_connect()`, `dpcm_be_disconnect()`, `snd_soc_runtime_action()`, and `dpcm_dapm_stream_event()` assert that `card->pcm_mutex` is held via `snd_soc_dpcm_mutex_assert_held()` checks, but callers such as `soc_compr_set_params_fe()`, `soc_compr_open_fe()`, and `soc_compr_free_fe()` invoke these functions without acquiring the mutex first. When `panic_on_warn` is enabled, the assertion failure triggers a kernel panic. The attack vector is local and requires opening a compress stream device. The fix involves repositioning and adding proper pcm_mutex locking in the compress stream code paths.
Affected products
- Linux Linux kernel versions affected by this ASoC soc-compress defect
Timeline
- 2025-12-09: disclosed: Published as CVE-2023-53866