CVE-2026-89757

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

mm/mglru: fix and remove redundant unevictable folio handling

sort_folio() has a shortcut for moving folios that are no longer evictable

but are still sitting on a generation list. However, this shortcut is

buggy. It does not follow the PG_lru usage convention, and it has a more

serious issue.

Unevictable folios are not threaded on lists[LRU_UNEVICTABLE], so that

folio->lru can be reused to hold folio->mlock_count (see the comment in

lruvec_init()). Hence lruvec_add_folio() skips the list_add() for them,

and every other place that turns a folio unevictable initialises

mlock_count explicitly: lru_add() sets it to 0, __mlock_folio() and

__mlock_new_folio() set it to !!folio_test_mlocked(folio). sort_folio()

sets nothing, and the lru_gen_del_folio() right above it may have already

poisoned folio->lru via list_del(), so mlock_count ends up aliasing

LIST_POISON2, which reads as 0x122, i.e. 290. The result is user

v

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References