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CVE PROGRAM SOURCE RECORD7.8 High

CVE-2025-22015

mm/migrate: fix shmem xarray update during migration

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: mm/migrate: fix shmem xarray update during migration A shmem folio can be either in page cache or in swap cache, but not at the same time. Namely, once it is in swap cache, folio->mapping should be NULL, and the folio is no longer in a shmem mapping. In __folio_migrate_mapping(), to determine the number of xarray entries to update, folio_test_swapbacked() is used, but that conflates shmem in page cache case and shmem in swap cache case. It leads to xarray multi-index entry corruption, since it turns a sibling entry to a normal entry during xas_store() (see [1] for a userspace reproduction). Fix it by only using folio_test_swapcache() to determine whether xarray is storing swap cache entries or not to choose the right number of xarray entries to update. [1] https://lore.kernel.org/linux-mm/Z8idPCkaJW1IChjT@casper.infradead.org/ Note: In __split_huge_page(), folio_test_anon() && folio_test_swapcache() is used to get swap_cache address space, but that ignores the shmem folio in swap cache case. It could lead to NULL pointer dereferencing when a in-swap-cache shmem folio is split at __xa_store(), since !folio_test_anon() is true and folio->mapping is NULL. But fortunately, its caller split_huge_page_to_list_to_order() bails out early with EBUSY when folio->mapping is NULL. So no need to take care of it here.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • be72d197b2281e2ee3f28017fc9be1ab17e26d16 to < 49100c0b070e900f87c8fac3be9b9ef8a30fa673affected
  • 07550b1461d4d0499165e7d6f7718cfd0e440427 to < 29124ae980e2860f0eec7355949d3d3292ee81daaffected
  • fc346d0a70a13d52fe1c4bc49516d83a42cd7c4c to < c057ee03f751d6cecf7ee64f52f6545d94082aaaaffected
  • fc346d0a70a13d52fe1c4bc49516d83a42cd7c4c to < 75cfb92eb63298d717b6b0118f91ba12c4fcfeb5affected
  • fc346d0a70a13d52fe1c4bc49516d83a42cd7c4c to < 60cf233b585cdf1f3c5e52d1225606b86acd08b0affected
  • 6.1.71 to < 6.1.132affected
  • 6.6.10 to < 6.6.85affected

Linux Linux

Default version status: affected

  • 6.7affected
  • 0 to < 6.7unaffected
  • 6.1.132 to ≤ 6.1.*unaffected
  • 6.6.85 to ≤ 6.6.*unaffected
  • 6.12.21 to ≤ 6.12.*unaffected
  • 6.13.9 to ≤ 6.13.*unaffected
  • 6.14 to ≤ *unaffected

References