Buffer Management Flaw in Linux Kernel Affecting Memory Operations

CVE-2025-71295

What is CVE-2025-71295?

A vulnerability exists in the Linux kernel related to buffer management during the memory release process. The function try_to_free_buffers() can erroneously be invoked on folios that lack attached buffers. This issue arises when filemap_release_folio() is called on a folio associated with a mapping holding the AS_RELEASE_ALWAYS flag, but without a corresponding release_folio operation defined. Consequently, while folio_needs_release() indicates that the folio should be released due to the AS_RELEASE_ALWAYS flag, the absence of private buffer data leads to an attempt to drop buffers on an empty folio, resulting in a null pointer dereference. A defensive measure has been implemented in the form of an early return from try_to_free_buffers() for folios without attached buffers, along with a warning to alert users about possible misconfigurations.

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