Bug 2461515 (CVE-2026-31589)

Summary: CVE-2026-31589 kernel: mm: call ->free_folio() directly in folio_unmap_invalidate()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's memory management. This vulnerability, known as a use-after-free, occurs when the system attempts to access a memory region after it has been released. Specifically, during the unmapping and invalidation of a memory page (folio), the system can incorrectly access a freed mapping structure. This can lead to memory corruption, potentially allowing an attacker to cause system instability or execute unauthorized code.
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Description OSIDB Bzimport 2026-04-24 15:06:01 UTC 
In the Linux kernel, the following vulnerability has been resolved:

mm: call ->free_folio() directly in folio_unmap_invalidate()

We can only call filemap_free_folio() if we have a reference to (or hold a
lock on) the mapping.  Otherwise, we've already removed the folio from the
mapping so it no longer pins the mapping and the mapping can be removed,
causing a use-after-free when accessing mapping->a_ops.

Follow the same pattern as __remove_mapping() and load the free_folio
function pointer before dropping the lock on the mapping.  That lets us
make filemap_free_folio() static as this was the only caller outside
filemap.c.
Comment 1 Keith Grant 2026-04-24 18:51:57 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042414-CVE-2026-31589-18ae@gregkh/T