CVE-2022-48717

What it actually does

Negative values for priv->gain in speaker_gain_control_put() bypass bounds checks, enabling out-of-bounds memory access originating from snd_ctl_elem_write_user() user input.

Why it matters to the business

Potential kernel instability or memory corruption on systems using the max9759 codec driver; low likelihood of remote exploitation reduces operational urgency despite widespread Linux kernel deployment.

How an attack unfolds

An attacker with local access crafts a negative gain value through the ALSA control interface; the unsanitized value reaches speaker_gain_control_put() and triggers an out-of-bounds read or write.

How to fix it

Apply the upstream fix present in commit a0f49d12547d45ea8b0f356a96632dd503941c1e or later; rebuild and deploy updated kernel packages containing the corrected max9759 driver.

How to confirm the fix worked

Verify the running kernel contains commit a0f49d12547d45ea8b0f356a96632dd503941c1e; confirm speaker_gain_control_put() now rejects negative gain values before indexing the gain table.

Typical attack path

1. Gain local access to a system running the vulnerable kernel
2. Open the ALSA mixer control for the max9759 device
3. Issue snd_ctl_elem_write with a negative gain value
4. Trigger out-of-bounds access inside speaker_gain_control_put()

How to detect it

Review kernel logs for oops or panic entries referencing max9759 or speaker_gain_control_put; inspect audit logs for unusual ALSA control writes from non-root processes.

What your security team should do

• Patch affected Linux kernels to the fixed commit within standard maintenance windows
• Audit systems exposing ALSA controls to untrusted local users
• Monitor EPSS and threat intelligence for any future increase in exploit maturity