CVE-2025-68179

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> s390: Disable ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP<br /> <br /> As reported by Luiz Capitulino enabling HVO on s390 leads to reproducible<br /> crashes. The problem is that kernel page tables are modified without<br /> flushing corresponding TLB entries.<br /> <br /> Even if it looks like the empty flush_tlb_all() implementation on s390 is<br /> the problem, it is actually a different problem: on s390 it is not allowed<br /> to replace an active/valid page table entry with another valid page table<br /> entry without the detour over an invalid entry. A direct replacement may<br /> lead to random crashes and/or data corruption.<br /> <br /> In order to invalidate an entry special instructions have to be used<br /> (e.g. ipte or idte). Alternatively there are also special instructions<br /> available which allow to replace a valid entry with a different valid<br /> entry (e.g. crdte or cspg).<br /> <br /> Given that the HVO code currently does not provide the hooks to allow for<br /> an implementation which is compliant with the s390 architecture<br /> requirements, disable ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP again, which is<br /> basically a revert of the original patch which enabled it.