CVE-2025-21696 (GCVE-0-2025-21696)

Vulnerability from cvelistv5 – Published: 2025-02-12 13:27 – Updated: 2025-10-01 19:57
VLAI?
Title
mm: clear uffd-wp PTE/PMD state on mremap()
Summary
In the Linux kernel, the following vulnerability has been resolved: mm: clear uffd-wp PTE/PMD state on mremap() When mremap()ing a memory region previously registered with userfaultfd as write-protected but without UFFD_FEATURE_EVENT_REMAP, an inconsistency in flag clearing leads to a mismatch between the vma flags (which have uffd-wp cleared) and the pte/pmd flags (which do not have uffd-wp cleared). This mismatch causes a subsequent mprotect(PROT_WRITE) to trigger a warning in page_table_check_pte_flags() due to setting the pte to writable while uffd-wp is still set. Fix this by always explicitly clearing the uffd-wp pte/pmd flags on any such mremap() so that the values are consistent with the existing clearing of VM_UFFD_WP. Be careful to clear the logical flag regardless of its physical form; a PTE bit, a swap PTE bit, or a PTE marker. Cover PTE, huge PMD and hugetlb paths.
Severity ?
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 , < 310ac886d68de661c3a334198d8604b722d7fdf8 (git)
Affected: 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 , < 0cef0bb836e3cfe00f08f9606c72abd72fe78ca3 (git)
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    Linux Linux Affected: 5.7
Unaffected: 0 , < 5.7 (semver)
Unaffected: 6.12.11 , ≤ 6.12.* (semver)
Unaffected: 6.13 , ≤ * (original_commit_for_fix)
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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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