CVE-2026-90315PCI/sysfs: Add lockdown checks to legacy I/O and memory handlers

Official 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_LEGACY (such as Alpha and PowerPC). [bhelgaas: add Link]

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/3556caa31a2bfbc22c11b812fd4ed8851c2d7bff
• https://git.kernel.org/stable/c/cd07aef510ac6a2873e01f9ddddc5492490b0067
• https://git.kernel.org/stable/c/747b9bbbbdfdee51aee2456388f9b94b5086de4d