CVE-2026-31568

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> s390/mm: Add missing secure storage access fixups for donated memory<br /> <br /> There are special cases where secure storage access exceptions happen<br /> in a kernel context for pages that don&amp;#39;t have the PG_arch_1 bit<br /> set. That bit is set for non-exported guest secure storage (memory)<br /> but is absent on storage donated to the Ultravisor since the kernel<br /> isn&amp;#39;t allowed to export donated pages.<br /> <br /> Prior to this patch we would try to export the page by calling<br /> arch_make_folio_accessible() which would instantly return since the<br /> arch bit is absent signifying that the page was already exported and<br /> no further action is necessary. This leads to secure storage access<br /> exception loops which can never be resolved.<br /> <br /> With this patch we unconditionally try to export and if that fails we<br /> fixup.