fkie_cve-2024-40950
Vulnerability from fkie_nvd
Published
2024-07-12 13:15
Modified
2024-11-21 09:31
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mm: huge_memory: fix misused mapping_large_folio_support() for anon folios When I did a large folios split test, a WARNING "[ 5059.122759][ T166] Cannot split file folio to non-0 order" was triggered. But the test cases are only for anonmous folios. while mapping_large_folio_support() is only reasonable for page cache folios. In split_huge_page_to_list_to_order(), the folio passed to mapping_large_folio_support() maybe anonmous folio. The folio_test_anon() check is missing. So the split of the anonmous THP is failed. This is also the same for shmem_mapping(). We'd better add a check for both. But the shmem_mapping() in __split_huge_page() is not involved, as for anonmous folios, the end parameter is set to -1, so (head[i].index >= end) is always false. shmem_mapping() is not called. Also add a VM_WARN_ON_ONCE() in mapping_large_folio_support() for anon mapping, So we can detect the wrong use more easily. THP folios maybe exist in the pagecache even the file system doesn't support large folio, it is because when CONFIG_TRANSPARENT_HUGEPAGE is enabled, khugepaged will try to collapse read-only file-backed pages to THP. But the mapping does not actually support multi order large folios properly. Using /sys/kernel/debug/split_huge_pages to verify this, with this patch, large anon THP is successfully split and the warning is ceased.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5df493a99fcf887133cf01d23cd4bebb6d385d3c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6a50c9b512f7734bc356f4bd47885a6f7c98491a
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/5df493a99fcf887133cf01d23cd4bebb6d385d3c
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/6a50c9b512f7734bc356f4bd47885a6f7c98491a
Impacted products
Vendor Product Version


To clipboard 

{
   cveTags: [],
   descriptions: [
      {
         lang: "en",
         value: "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: huge_memory: fix misused mapping_large_folio_support() for anon folios\n\nWhen I did a large folios split test, a WARNING \"[ 5059.122759][ T166]\nCannot split file folio to non-0 order\" was triggered.  But the test cases\nare only for anonmous folios.  while mapping_large_folio_support() is only\nreasonable for page cache folios.\n\nIn split_huge_page_to_list_to_order(), the folio passed to\nmapping_large_folio_support() maybe anonmous folio.  The folio_test_anon()\ncheck is missing.  So the split of the anonmous THP is failed.  This is\nalso the same for shmem_mapping().  We'd better add a check for both.  But\nthe shmem_mapping() in __split_huge_page() is not involved, as for\nanonmous folios, the end parameter is set to -1, so (head[i].index >= end)\nis always false.  shmem_mapping() is not called.\n\nAlso add a VM_WARN_ON_ONCE() in mapping_large_folio_support() for anon\nmapping, So we can detect the wrong use more easily.\n\nTHP folios maybe exist in the pagecache even the file system doesn't\nsupport large folio, it is because when CONFIG_TRANSPARENT_HUGEPAGE is\nenabled, khugepaged will try to collapse read-only file-backed pages to\nTHP.  But the mapping does not actually support multi order large folios\nproperly.\n\nUsing /sys/kernel/debug/split_huge_pages to verify this, with this patch,\nlarge anon THP is successfully split and the warning is ceased.",
      },
      {
         lang: "es",
         value: "En el kernel de Linux, se resolvió la siguiente vulnerabilidad: mm: enorme_memoria: corrige el mapeo_grande_folio_support() mal utilizado para publicaciones anónimas Cuando hice una prueba de división de publicaciones grandes, apareció una ADVERTENCIA \"[ 5059.122759][ T166] No se puede dividir la publicación del archivo en un valor distinto de 0 \"orden\" se activó. Pero los casos de prueba son sólo para folios anónimos. mientras que mapping_large_folio_support() solo es razonable para las publicaciones de caché de páginas. En split_huge_page_to_list_to_order(), la publicación pasó a mapping_large_folio_support(), tal vez una publicación anónima. Falta la verificación folio_test_anon(). Así que la división del THP anónimo fracasó. Esto también es lo mismo para shmem_mapping(). Será mejor que agreguemos un cheque para ambos. Pero shmem_mapping() en __split_huge_page() no está involucrado, ya que para las publicaciones anónimas, el parámetro final se establece en -1, por lo que (head[i].index >= end) siempre es falso. shmem_mapping() no se llama. También agregue un VM_WARN_ON_ONCE() en mapping_large_folio_support() para un mapeo anónimo, para que podamos detectar el uso incorrecto más fácilmente. Es posible que existan publicaciones de THP en el caché de páginas, incluso si el sistema de archivos no admite publicaciones grandes, esto se debe a que cuando CONFIG_TRANSPARENT_HUGEPAGE está habilitado, khugepaged intentará colapsar las páginas respaldadas por archivos de solo lectura en THP. Pero el mapeo en realidad no admite correctamente folios grandes de varios pedidos. Usando /sys/kernel/debug/split_huge_pages para verificar esto, con este parche, un THP anónimo grande se divide con éxito y la advertencia cesa.",
      },
   ],
   id: "CVE-2024-40950",
   lastModified: "2024-11-21T09:31:55.947",
   metrics: {},
   published: "2024-07-12T13:15:17.353",
   references: [
      {
         source: "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
         url: "https://git.kernel.org/stable/c/5df493a99fcf887133cf01d23cd4bebb6d385d3c",
      },
      {
         source: "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
         url: "https://git.kernel.org/stable/c/6a50c9b512f7734bc356f4bd47885a6f7c98491a",
      },
      {
         source: "af854a3a-2127-422b-91ae-364da2661108",
         url: "https://git.kernel.org/stable/c/5df493a99fcf887133cf01d23cd4bebb6d385d3c",
      },
      {
         source: "af854a3a-2127-422b-91ae-364da2661108",
         url: "https://git.kernel.org/stable/c/6a50c9b512f7734bc356f4bd47885a6f7c98491a",
      },
   ],
   sourceIdentifier: "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
   vulnStatus: "Awaiting Analysis",
}


Log in or create an account to share your comment.

Security Advisory comment format.

This schema specifies the format of a comment related to a security advisory.

UUIDv4 of the comment
UUIDv4 of the Vulnerability-Lookup instance
When the comment was created originally
When the comment was last updated
Title of the comment
Description of the comment
The identifier of the vulnerability (CVE ID, GHSA-ID, PYSEC ID, etc.).



Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.