CVE-2026-64216

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

netfs: Fix potential UAF in netfs_unlock_abandoned_read_pages()

netfs_unlock_abandoned_read_pages(rreq) accesses the index of the folios it is wanting to unlock and compares that to rreq->no_unlock_folio so that it doesnt unlock a folio being read for netfs_perform_write() or netfs_write_begin().

However, given that netfs_unlock_abandoned_read_pages() is called after NETFS_RREQ_IN_PROGRESS is cleared, the one folio that its not allowed to dereference is the one specified by ->no_unlock_folio as ownership immediately reverts to the caller.

Fix this by storing the folio pointer instead and using that rather than the index. Also fix netfs_unlock_read_folio() where the same applies.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/3866d015f33aeedf81338dd99154703bef33faef
• https://git.kernel.org/stable/c/6080fa3ecfbb4448a3b47368629534c09b6ec750
• https://git.kernel.org/stable/c/dbe556972100fabb8e5a1b3d2163831ff07b1e8e