mm/page_table_check: skip special zero mappings

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74600
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:32 UTC
Updated2026-08-23 13:16:46 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mm/page_table_check: skip special zero mappings page_table_check_set() and page_table_check_clear() account mappings based on PageAnon(). Shared zero-page PTEs and huge zero PMDs are special mappings, but page_table_check can still account them as file-backed pages. An unprivileged process can populate enough zero mappings to overflow file_map_count and hit the existing BUG_ON(). The PTE path can do this with the shared zero page, and the PMD path can do the same with huge zero mappings. Skip special zero mappings in the user page-table accounting paths. Keep the PTE-side pte_special() check, and identify huge zero PMDs from the mapped folio instead of pmd_special(). That covers architectures where pmd_special() is a no-op without adding huge_zero_pfn checks to the generic counter helpers.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected df4e817b710809425d899340dbfa8504a3ca4ba5 7755be923e325dc300f4b0c3e1ad7e91b28b3cb9 git Not specified
CNA Linux Linux affected df4e817b710809425d899340dbfa8504a3ca4ba5 b726eb3c94d23e09da0e0f46b0fa09fb2b5d99cc git Not specified
CNA Linux Linux affected df4e817b710809425d899340dbfa8504a3ca4ba5 8db4bab826ccc9ec10fa41736a48031cd338d392 git Not specified
CNA Linux Linux affected 5.17 Not specified
CNA Linux Linux unaffected 5.17 semver Not specified
CNA Linux Linux unaffected 6.18.46 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/8db4bab826ccc9ec10fa41736a48031cd338d392 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7755be923e325dc300f4b0c3e1ad7e91b28b3cb9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b726eb3c94d23e09da0e0f46b0fa09fb2b5d99cc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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