DEBIAN-CVE-2026-64216

In the Linux kernel, the following vulnerability has been resolved:  netfs: Fix potential UAF in netfsunlockabandonedreadpages()  netfsunlockabandonedreadpages(rreq) accesses the index of the folios it is wanting to unlock and compares that to rreq->nounlockfolio so that it doesn't unlock a folio being read for netfsperformwrite() or netfswritebegin().  However, given that netfsunlockabandonedreadpages() is called after NETFSRREQINPROGRESS is cleared, the one folio that it's not allowed to dereference is the one specified by ->nounlockfolio as ownership immediately reverts to the caller.  Fix this by storing the folio pointer instead and using that rather than the index.  Also fix netfsunlockreadfolio() where the same applies.