Linux Kernel up to 7.2.5 locking

Summaryinfo

A vulnerability described as very critical has been identified in Linux Kernel up to 7.2.5. This vulnerability affects the function pci_write_legacy_io/pci_mmap_legacy_mem/pci_mmap_legacy_io. Such manipulation leads to locking. This vulnerability is listed as CVE-2026-90315. The attack must be carried out locally. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in Linux Kernel up to 7.2.5. Affected by this issue is the function pci_write_legacy_io/pci_mmap_legacy_mem/pci_mmap_legacy_io. The manipulation with an unknown input leads to a locking vulnerability. Using CWE to declare the problem leads to CWE-667. The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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]

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-90315 since 09/11/2026. The exploitation is known to be easy. Local access is required to approach this attack. Additional levels of successful authentication are necessary for exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 09/17/2026).

Upgrading to version 7.2.6 or 7.3-rc1 eliminates this vulnerability. Applying the patch cd07aef510ac6a2873e01f9ddddc5492490b0067/747b9bbbbdfdee51aee2456388f9b94b5086de4d is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

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