CVE-2024-46773

What it actually does

A missing check allows a zero denominator (pbn_div) to reach a division operation in the AMD display driver code path, triggering a kernel divide-by-zero fault.

Why it matters to the business

Systems using affected AMD GPUs may experience sudden kernel crashes or display subsystem failures, leading to downtime and loss of graphics functionality until the system is restarted or patched.

How an attack unfolds

An attacker with local access crafts display configuration parameters that result in a zero pbn_div value being passed to the unchecked division, causing the kernel to fault. No remote vector or known public exploit exists.

How to fix it

Update the Linux kernel to a version containing commit 20e7164c52d9bfbb9d9862b833fa989624a61345 or later stable releases that include the pbn_div validation. Reboot after applying the update.

How to confirm the fix worked

Verify the running kernel contains the fix commit or inspect the drm/amd/display source to confirm the denominator check precedes any division using pbn_div; test with synthetic zero-denominator inputs if possible in a lab environment.

Typical attack path

1. Obtain local user or process execution on the target Linux system
2. Trigger AMD display driver code paths that calculate pbn_div from user-supplied or hardware-derived values
3. Force pbn_div to evaluate to zero
4. Reach the division operation resulting in kernel panic or oops

How to detect it

Review kernel logs (dmesg, /var/log/kern.log, journalctl) for divide-by-zero or oops messages referencing amd_display or pbn_div; correlate with process activity that interacts with the DRM subsystem.

What your security team should do

• Prioritize patching kernel packages on all AMD GPU systems within standard maintenance windows
• Monitor vendor advisories for backported fixes in distribution kernels
• Restrict unprivileged local access on high-value graphics workstations until updated