CVE-2024-36479

What it actually does

Null pointer dereference in fpga_bridge_get and related functions when the parent device lacks a driver, because the fpga_bridge struct previously relied on the parent driver's owner pointer instead of storing its own module owner reference.

Why it matters to the business

Linux systems using FPGA bridges risk kernel crashes or instability during bridge operations, which can disrupt hardware-accelerated workloads or embedded device functionality until patched.

How an attack unfolds

An attacker triggers fpga_bridge_get or of_fpga_bridge_get on a system where the parent device has no driver registered, causing the kernel to dereference a null owner pointer and resulting in a crash or potential further exploitation of the resulting memory corruption.

How to fix it

Update the Linux kernel to the fixed commit 18dc8366abb6cadcb77668b1a16434654e355d49 which adds an owner module pointer to the fpga_bridge struct, updates registration functions, and adjusts refcount handling.

How to confirm the fix worked

Inspect kernel source for the fpga_bridge struct containing an owner field and confirm fpga_bridge_register_owner or the helper macro is used; check dmesg for absence of null dereference oops in fpga bridge code after upgrade.

Typical attack path

1. Locate a Linux system exposing FPGA bridge registration paths
2. Ensure or force a parent device without an associated driver
3. Invoke bridge get functions to trigger the missing owner dereference
4. Exploit resulting null pointer dereference for denial of service or memory corruption

How to detect it

Search kernel logs and crash dumps for null pointer dereference faults originating from fpga_bridge_get, of_fpga_bridge_get, or __fpga_bridge_get; review module loading and device registration events around FPGA bridge usage.

What your security team should do

• Apply the kernel update containing commit 18dc8366abb6cadcb77668b1a16434654e355d49 immediately on affected systems
• Audit custom FPGA bridge drivers for use of the updated registration interface
• Monitor kernel logs for fpga bridge related null pointer dereferences
• Limit exposure of FPGA bridge interfaces to untrusted code until patched