CVE-2024-56785

What it actually does

Device tree source for Loongson64 PCIe ports on MIPS lacks required #interrupt-cells and #address-cells properties, triggering dtc warnings during build and a runtime warning in of_bus_n_addr_cells during kernel initialization.

Why it matters to the business

Systems using affected Loongson64 hardware may experience boot-time warnings or degraded device-tree parsing reliability; the issue is low severity and not known to be actively exploited.

How an attack unfolds

An attacker with local access or the ability to supply a malicious device tree could trigger the misconfigured PCIe node handling, but the flaw primarily manifests as warnings rather than direct code execution.

How to fix it

Apply the upstream fix present in the resolved commit; for listed chromium-browser packages on Ubuntu 14.04 LTS upgrade to version 53.0.2785.143-0ubuntu0.14.04.1.1142 or later kernel packages that incorporate the DTS correction.

How to confirm the fix worked

Rebuild and inspect the dtb with dtc to confirm absence of interrupt_provider and interrupt_map warnings; boot the system and verify no WARNING at drivers/of/base.c:106 occurs for the pci_bridge node.

Typical attack path

1. Identify Loongson64-based MIPS system running vulnerable kernel DTS
2. Supply or modify device tree to reference the incomplete pci@1a000000 node
3. Observe dtc or runtime warnings during kernel boot or device enumeration

How to detect it

Review kernel boot logs for of_bus_n_addr_cells warnings referencing /bus@10000000/pci@1a000000; examine dtc output from affected device-tree builds for interrupt_provider warnings.

What your security team should do

• Prioritize kernel package updates on all Loongson64 MIPS systems
• Audit device-tree sources for missing #address-cells and #interrupt-cells on PCI nodes
• Monitor EPSS and KEV status; no immediate action required given low scores and non-KEV status