CVE-2026-90315

/// Technical description

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

PCI/sysfs: Add lockdown checks to legacy I/O and memory handlers

Currently, the legacy I/O and memory sysfs handlers do not check

security_locked_down(LOCKDOWN_PCI_ACCESS), leaving the legacy_io and

legacy_mem files unprotected when the kernel is locked down.

Commit eb627e17727e ("PCI: Lock down BAR access when the kernel is locked

down") added the check to pci_write_config(), pci_mmap_resource(), and

pci_write_resource_io() to prevent userspace from programming DMA-capable

hardware that could be used to modify kernel code, but did not cover the

legacy handlers.

As a result, root can still write arbitrary I/O ports and map the legacy

I/O and memory spaces while the kernel is locked down, which is the same

capability the lockdown is meant to remove.

Add the same check to pci_write_legacy_io(), pci_mmap_legacy_mem(), and

pci_mmap_legacy_io().

These generic handlers cover both architectures that define HAVE_PCI_LEGA

/// 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