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

Summary

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]

Timeline

1. Sep 17, 2026, 4:08 PM UTCCVE published
2. Oct 19, 2026, 9:01 AM UTCRecord last updated

Affected versions

• Linux Linux

  From eb627e17727ebeede70697ae1798688b0d328b54 · fixed in 3556caa31a2bfbc22c11b812fd4ed8851c2d7bff; From eb627e17727ebeede70697ae1798688b0d328b54 · fixed in cd07aef510ac6a2873e01f9ddddc5492490b0067; From eb627e17727ebeede70697ae1798688b0d328b54 · fixed in 747b9bbbbdfdee51aee2456388f9b94b5086de4d

• Linux Linux

  5.4

• KernelLinux

  From 5.4.0 · fixed in 6.18.57; From 6.19.0 · fixed in 7.2.6

References 3