CVE-2024-50187

What it actually does

Use-after-free in Linux kernel vc4 DRM driver: active_perfmon pointer retained after owning process exits and perfmons are freed in vc4_perfmon_close_file, causing later jobs to dereference invalid memory when stopping the monitor.

Why it matters to the business

Potential kernel instability, crashes, or local privilege escalation on vc4-equipped systems; low EPSS and no KEV status indicate limited observed exploitation but still requires patching on graphics-enabled Linux hosts.

How an attack unfolds

Attacker opens DRM file descriptor, activates a perfmon, closes the descriptor (leaving stale active_perfmon), then opens a new descriptor and submits jobs that trigger vc4 to stop the now-freed monitor pointer.

How to fix it

Apply upstream kernel fix that explicitly stops the active perfmon before destruction in vc4_perfmon_close_file; update to patched kernel versions; no specific fixed package versions provided for the listed browsers.

How to confirm the fix worked

Confirm kernel source contains the stop-before-destroy logic for active_perfmon; test by exercising perfmon lifecycle across process boundaries and verify absence of use-after-free warnings or crashes.

Typical attack path

1. Open DRM file descriptor and start a performance monitor
2. Close the file descriptor without stopping the active monitor
3. Open a new file descriptor and submit jobs referencing performance monitors
4. Trigger driver code path that dereferences the stale vc4->active_perfmon pointer

How to detect it

Search kernel logs for vc4 perfmon oops, use-after-free warnings, or panics following process exits that used DRM performance monitors; correlate with new DRM file descriptor activity from different processes.

What your security team should do

• Patch affected Linux kernels promptly despite low EPSS
• Restrict unprivileged access to DRM perfmon interfaces on vc4 hardware
• Monitor kernel logs for vc4-related oops or use-after-free reports
• Audit systems for vc4 DRM usage and prioritize updates on Raspberry Pi and similar platforms