CVE-2024-35922

What it actually does

Division by zero in fb_videomode_from_videomode() when htotal * vtotal overflows to zero, causing kernel crash with availability impact.

Why it matters to the business

Local users on affected Linux systems can trigger kernel crashes leading to system downtime and loss of availability during video mode handling operations.

How an attack unfolds

A local attacker supplies crafted video mode parameters that cause integer overflow in htotal * vtotal, resulting in division by zero when the function attempts the operation.

How to fix it

Upgrade the Linux kernel to a version containing commit 1fb52bc1de55e9e0bdf71fe078efd4da0889710f or later stable releases that include the division-by-zero guard.

How to confirm the fix worked

Verify the presence of the fix commit in the kernel source or confirm the kernel version includes the updated fbmon logic; test by exercising video mode conversion paths without triggering faults.

Typical attack path

1. Obtain local user access on a Linux system running an affected kernel
2. Trigger framebuffer video mode conversion via user-space APIs or tools
3. Supply parameters that overflow htotal * vtotal to zero
4. Cause division by zero fault leading to kernel oops or panic

How to detect it

Review kernel logs for oops or panic messages referencing fb_videomode_from_videomode or division by zero in fbmon; correlate with local process activity around framebuffer operations.

• fb_videomode_from_videomode
• division by zero in fbmon

What your security team should do

• Apply the kernel update containing commit 1fb52bc1de55e9e0bdf71fe078efd4da0889710f as soon as possible
• Monitor for local privilege or crash reports involving fbmon
• Restrict untrusted local access on systems running vulnerable kernels