CVE-2022-3303

What it actually does

Race condition from improper locking in the Linux kernel sound subsystem allows a NULL pointer dereference when processing the SNDCTL_DSP_SYNC ioctl, resulting in kernel panic.

Why it matters to the business

Privileged local users can intentionally crash affected Linux systems, causing denial of service that disrupts services, workloads, and availability on servers or desktops until reboot.

How an attack unfolds

An attacker with local access as root or audio group member opens an audio device and issues the SNDCTL_DSP_SYNC ioctl in a timing window that exploits the missing lock, dereferencing a NULL pointer and crashing the kernel.

How to fix it

Upgrade the Linux kernel to commit 8423f0b6d513b259fdab9c9bf4aaa6188d054c2d or any later mainline or distribution-patched release that contains the fix; rebuild and reboot into the updated kernel.

How to confirm the fix worked

Verify the running kernel contains commit 8423f0b6d513b259fdab9c9bf4aaa6188d054c2d via git log or package version; test that the SNDCTL_DSP_SYNC ioctl no longer produces a NULL dereference under concurrent load.

Typical attack path

1. Obtain local shell as root or member of the audio group
2. Open an audio device node such as /dev/dsp
3. Invoke the SNDCTL_DSP_SYNC ioctl while racing against concurrent operations
4. Trigger NULL pointer dereference leading to kernel panic and reboot

How to detect it

Search kernel logs and dmesg for oops or panic messages referencing the sound subsystem, NULL pointer dereference, and SNDCTL_DSP_SYNC ioctl calls; correlate with user sessions holding audio device file descriptors.

What your security team should do

• Prioritize kernel updates on all systems exposing audio devices to untrusted local users
• Apply updates within standard change windows given the low EPSS and lack of KEV listing
• Restrict audio group membership to only required service accounts
• Monitor kernel logs for sound-subsystem oops entries as a compensating control