CVE-2024-35993
Assigner: Linux
Published: 2024-05-20T09:47:57.739Z
State: PUBLISHED
descriptions: value: In the Linux kernel, the following vulnerability has been resolved:

mm: turn folio_test_hugetlb into a PageType

The current folio_test_hugetlb() can be fooled by a concurrent folio split
into returning true for a folio which has never belonged to hugetlbfs. 
This can't happen if the caller holds a refcount on it, but we have a few
places (memory-failure, compaction, procfs) which do not and should not
take a speculative reference.

Since hugetlb pages do not use individual page mapcounts (they are always
fully mapped and use the entire_mapcount field to record the number of
mappings), the PageType field is available now that page_mapcount()
ignores the value in this field.

In compaction and with CONFIG_DEBUG_VM enabled, the current implementation
can result in an oops, as reported by Luis. This happens since 9c5ccf2db04b
("mm: remove HUGETLB_PAGE_DTOR") effectively added some VM_BUG_ON() checks
in the PageHuge() testing path.

[willy@infradead.org: update vmcoreinfo]
  Link: https://lkml.kernel.org/r/ZgGZUvsdhaT1Va-T@casper.infradead.org
affected: product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions: version: 9c5ccf2db04b
lessThan: 2431b5f2650d
status: affected
versionType: git
version: 9c5ccf2db04b
lessThan: 9fdcc5b6359d
status: affected
versionType: git
version: 9c5ccf2db04b
lessThan: d99e3140a4d3
status: affected
versionType: git
product: Linux
vendor: Linux
defaultStatus: affected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions: version: 6.6
status: affected
version: 0
lessThan: 6.6
status: unaffected
versionType: custom
version: 6.6.30
lessThanOrEqual: 6.6.*
status: unaffected
versionType: custom
version: 6.8.9
lessThanOrEqual: 6.8.*
status: unaffected
versionType: custom
version: 6.9
lessThanOrEqual: *
status: unaffected
versionType: original_commit_for_fix
title: mm: turn folio_test_hugetlb into a PageType
x_generator: engine: bippy-d175d3acf727