Linux Kernel up to 7.2.3 Device-Private PMD madvise_cold_or_pageout_pte_range race condition

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.2.3 and classified as critical. This affects the function madvise_cold_or_pageout_pte_range of the component Device-Private PMD Handler. Such manipulation leads to race condition. This vulnerability is documented as CVE-2026-93217. The attack needs to be performed locally. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.2.3 and classified as critical. Affected by this issue is the function madvise_cold_or_pageout_pte_range of the component Device-Private PMD Handler. The manipulation with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. Impacted is availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: mm/madvise: skip device-private PMDs in cold and pageout walks madvise_cold_or_pageout_pte_range() takes pmd_trans_huge_lock(), whose pmd_is_huge() check returns true for a device-private PMD. The subsequent !pmd_present() branch has a VM_BUG_ON() asserting migration is the only allowed non-present case; a device-private PMD trips it. Skip device-private PMDs in that non-present branch and continue to huge_unlock before calling pmd_folio(). Downgrade the check to VM_WARN_ON_ONCE() so an unexpected PMD softleaf logs a warning rather than panicking. Drop the thp_migration_supported() guard: it expands to IS_ENABLED(CONFIG_ARCH_SUPPORTS_PMD_SOFTLEAF), and both pmd_is_migration_entry() and pmd_is_device_private_entry() already return false when that config is not selected, so the guard suppresses only the case where the warning would already be silent. Potential trigger: an HMM-based GPU driver races with madvise(MADV_COLD)/MADV_PAGEOUT: pmd_trans_huge(*pmd) reads true, then migrate_vma_pages() flips the PMD to a device-private entry before the PMD lock is acquired.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-93217 since 09/17/2026. The exploitation is known to be easy. Local access is required to approach this attack. Technical details are known, but there is no available exploit.

Upgrading to version 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch 5c0d7b658cda62cd17cb3652783386d5608030ef/d4b76d0b03cb49611312ecc4bcfb55ccdf0843e2 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

License

• open-source

Website

• Vendor: https://www.kernel.org/

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