CVE-2024-42120

What it actually does

Missing bounds check on pipe index before array access in AMD display driver leads to potential out-of-bounds memory access (overrun) when handling vblank events.

Why it matters to the business

Kernel instability or crashes on affected Linux systems using AMD graphics, potentially enabling local privilege escalation or denial of service; widespread impact due to Linux kernel prevalence in servers, desktops, and embedded devices.

How an attack unfolds

An attacker with local access triggers display code paths that supply an out-of-range pipe index, causing the driver to access memory beyond the allocated pipe_ctx array; this can corrupt kernel structures or allow controlled memory writes depending on attacker-supplied data.

How to fix it

Update the Linux kernel to a version containing commit b2e9abc95583ac7bbb2c47da4d476a798146dfd6 or later; rebuild and reboot with the patched kernel; apply vendor backports for stable distributions.

How to confirm the fix worked

Verify the running kernel contains commit b2e9abc95583ac7bbb2c47da4d476a798146dfd6 via git log or package version; recompile with Coverity or similar static analysis to confirm the bounds check is present; test display initialization and vblank handling under load.

Typical attack path

1. Obtain local user or unprivileged process access on a Linux system with AMD display hardware
2. Trigger graphics or display operations that reach the vblank handling code in the AMD driver
3. Supply or induce an invalid pipe offset exceeding MAX_PIPES
4. Cause array overrun leading to memory corruption or crash
5. Leverage corruption for privilege escalation or denial of service if exploitation conditions are met

How to detect it

Review kernel logs for AMD display driver crashes, oops, or warnings referencing pipe_ctx or vblank; inspect for unexpected display subsystem faults around graphics initialization; correlate with local user activity preceding the event.

What your security team should do

• Prioritize kernel updates on all AMD GPU systems within standard patch cycles
• Monitor for upstream stable kernel releases incorporating the fix
• Restrict untrusted local code execution where possible until patched
• Include kernel version checks in vulnerability scanning and asset inventories