CVE-2024-56760

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

PCI/MSI: Handle lack of irqdomain gracefully

Alexandre observed a warning emitted from pci_msi_setup_msi_irqs() on a

RISCV platform which does not provide PCI/MSI support:

WARNING: CPU: 1 PID: 1 at drivers/pci/msi/msi.h:121 pci_msi_setup_msi_irqs+0x2c/0x32

__pci_enable_msix_range+0x30c/0x596

pci_msi_setup_msi_irqs+0x2c/0x32

pci_alloc_irq_vectors_affinity+0xb8/0xe2

RISCV uses hierarchical interrupt domains and correctly does not implement

the legacy fallback. The warning triggers from the legacy fallback stub.

That warning is bogus as the PCI/MSI layer knows whether a PCI/MSI parent

domain is associated with the device or not. There is a check for MSI-X,

which has a legacy assumption. But that legacy fallback assumption is only

valid when legacy support is enabled, but otherwise the check should simply

return -ENOTSUPP.

Loongarch tripped over the same problem and blindly enabled legacy support

without implemen

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References