CVE-2022-49005

What it actually does

The vulnerability is an incorrect bounds check in snd_soc_put_volsw_sx() for _sx ALSA controls; the max field represents step count rather than an absolute maximum value, allowing out-of-bounds or invalid control values to be accepted.

Why it matters to the business

Systems running affected Linux kernels may experience audio subsystem instability or crashes when untrusted users or applications interact with certain mixer controls, impacting multimedia and embedded device functionality.

How an attack unfolds

An attacker with access to ALSA mixer controls crafts a malicious put operation that supplies a value exceeding the intended range; because the bounds check uses the wrong semantic for max, the kernel accepts the value and performs an out-of-bounds write or read in the control handling path.

How to fix it

Upgrade the Linux kernel to a version containing commit f443e374ae131c168a065ea1748feac6b2e76613 or later; rebuild and reboot with the patched kernel.

How to confirm the fix worked

Verify the running kernel contains commit f443e374ae131c168a065ea1748feac6b2e76613 via git log or kernel version string; test that _sx control values are now properly clamped.

Typical attack path

1. Obtain local or container access to a system using the vulnerable kernel
2. Locate an _sx volume control exposed by the sound card driver
3. Issue a snd_soc_put_volsw_sx ioctl with a value larger than the actual maximum
4. Trigger the missing bounds validation leading to invalid memory access

How to detect it

Review kernel logs for oops or warnings originating from snd_soc_put_volsw_sx or ASoC control handling around the time of suspected exploitation; look for unusual ALSA ioctl sequences in audit logs.

What your security team should do

• Prioritize kernel updates on all systems exposing ALSA controls to untrusted users
• Monitor for downstream distribution packages that back-port the referenced commit
• Restrict unprivileged access to ALSA mixer devices where feasible until patched