CVE-2022-48738

What it actually does

snd_soc_put_volsw() accepted volume values outside the advertised min/max range without validation, allowing userspace to supply out-of-bounds integers that could reach downstream mixer or codec logic.

Why it matters to the business

Audio subsystems on affected Linux kernels could receive malformed control settings, resulting in unexpected device behavior, degraded audio quality, or kernel instability on systems that expose ALSA volume controls to untrusted callers.

How an attack unfolds

An attacker with access to an ALSA mixer control interface sends crafted out-of-range integer values through snd_soc_put_volsw(); because no range check existed, the values propagate into the audio driver, potentially triggering incorrect calculations or state corruption.

How to fix it

Upgrade the Linux kernel to a version containing commit 40f598698129b5ceaf31012f9501b775c7b6e57d or later; rebuild and reboot with the patched kernel. Where immediate upgrade is not possible, restrict unprivileged access to ALSA control devices via device permissions or SELinux/AppArmor policies.

How to confirm the fix worked

Confirm the running kernel git tree contains commit 40f598698129b5ceaf31012f9501b775c7b6e57d, or verify that snd_soc_put_volsw() now explicitly rejects values outside the declared min/max bounds via source inspection or runtime tracing of the function.

Typical attack path

1. Identify a system exposing ALSA volume controls via /dev/snd/controlC*
2. Open the control device and locate a snd_soc volume switch element
3. Issue a put operation with an integer outside the advertised range
4. Observe resulting audio misbehavior or kernel fault in the codec or mixer path

How to detect it

Review kernel logs for ALSA or ASoC errors around volume control operations; inspect auditd or seccomp logs for unusual access to /dev/snd/control* devices; correlate with process execution that interacts with ALSA mixer APIs.

What your security team should do

• Apply the referenced kernel commit or distribution update within standard patch windows
• Audit systems for custom ALSA user-space components that might supply unvalidated control values
• Monitor EPSS and KEV status for any future increase in exploit maturity