CVE-2023-54072

What it actually does

Race condition in ALSA PCM memory allocation allows bypassing a soft limit on total buffer allocations because the size check and allocation are not protected by card->memory_mutex, permitting allocation of more memory than the predefined maximum.

Why it matters to the business

Systems running affected Linux kernels may experience inconsistent memory accounting and slightly higher memory consumption than intended under concurrent PCM buffer allocation workloads, though the impact remains limited and no widespread exploitation has been observed.

How an attack unfolds

An attacker with local access triggers concurrent PCM memory allocation requests; without the mutex, multiple threads pass the size check simultaneously and allocate beyond the limit before the accounting is updated, resulting in excess memory usage.

How to fix it

Update to a fixed kernel containing commit 7e1d1456c8db9949459c5a24e8845cfe92430b0f or later; for MinimOS packages upgrade mysql-8.4, mysql-8.4-dev, mysql-8.4-client and related entries to 8.4.6-r0 or newer.

How to confirm the fix worked

Confirm the presence of commit 7e1d1456c8db9949459c5a24e8845cfe92430b0f in the kernel source or verify package versions match the listed fixed releases; review ALSA PCM allocation paths for mutex coverage around size checks.

Typical attack path

1. Obtain local user access on a system running an affected kernel
2. Open multiple PCM devices or issue concurrent buffer allocation ioctls
3. Race the unprotected size check in do_alloc_pages() to exceed the max allocation limit
4. Observe or leverage the resulting excess memory consumption

How to detect it

Review kernel logs and audit records for repeated PCM allocation calls around the time of any unexpected memory spikes; examine source history for the mutex addition around do_alloc_pages().

What your security team should do

• Prioritize kernel updates on systems with heavy ALSA/PCM usage
• Monitor for any unusual memory growth in audio-related processes after patching
• Apply fixes within standard maintenance windows given low EPSS and lack of KEV listing