CVE-2023-52821

What it actually does

In versatile_panel_get_modes(), the return value of drm_mode_duplicate() is assigned to mode without a NULL check, leading to a null pointer dereference on allocation failure and a kernel crash.

Why it matters to the business

Linux systems using affected display panel drivers may experience unexpected crashes and downtime, disrupting operations and requiring manual intervention or reboots.

How an attack unfolds

An attacker with local access triggers display mode enumeration in the DRM panel driver under conditions where drm_mode_duplicate() fails (such as low memory), causing the kernel to dereference a NULL pointer and panic.

How to fix it

Upgrade the Linux kernel to a version containing commit c7dc0aca5962fb37dbea9769dd26ec37813faae1, which adds the missing NULL check after drm_mode_duplicate().

How to confirm the fix worked

Inspect the kernel source for the presence of the NULL check on the mode pointer returned by drm_mode_duplicate() inside versatile_panel_get_modes(); verify the running kernel includes the referenced commit.

Typical attack path

1. Obtain local user access on the target Linux system
2. Trigger versatile_panel_get_modes() via graphics or display operations
3. Induce resource exhaustion or allocation failure in drm_mode_duplicate()
4. Cause kernel null pointer dereference and system crash

How to detect it

Search kernel logs, dmesg output, and crash dumps for oops or panic messages mentioning versatile_panel_get_modes or drm_mode_duplicate failures.

• versatile_panel_get_modes
• drm_mode_duplicate

What your security team should do

• Apply the fixed kernel commit or a distribution update containing it as soon as possible
• Review and restrict local access to systems running vulnerable kernels
• Monitor kernel logs for panics referencing versatile_panel or drm_mode_duplicate