Technical impact
This vulnerability is the result of reverting a prior fix that added necessary locking in the ALSA ASoC fsl_xcvr driver. The revert re‑introduces a scenario in which fsl_xcvr_mode_put() attempts to acquire the same read lock while already holding the write lock, causing a deadlock that can freeze kernel threads and expose the system to a denial‑of‑service condition within the audio subsystem. This is a classic example of CWE‑667 synchronization error, where a thread holds a write lock and then attempts to acquire a read lock, leading to a deadlock. It may also involve incorrect usage patterns that relate to CWE‑833.
Affected Systems
Affected systems include Linux kernels 5.15.201, 6.1.164, 6.12.74, 6.18.13, 6.19, and 6.6.127, all of which contain the reverted commit that removed locking from fsl_xcvr_mode_put().
Risk and Exploitability
The flaw can be triggered by a local user who can write to ALSA control elements, driving the vulnerable code path in fsl_xcvr_mode_put(). The vulnerability manifests as a deadlock and a hung task in kernel space, causing a denial‑of‑service to the audio subsystem. The CVSS score of 5.5 indicates a moderate severity, and the EPSS score of 0.00032 (less than 1%) shows a very low probability of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog, suggesting it has not yet been actively exploited. The affected kernel releases include 5.15.201, 6.1.164, 6.12.74, 6.18.13, 6.19, and 6.6.127, which all contain the reversed commit that removed the lock.
