Executive brief
A vulnerability in the Linux kernel for s390 architecture systems could lead to system crashes or data corruption. The issue occurs when the system attempts to optimize memory management for large memory pages (HugeTLB) in a way that is incompatible with the specific hardware requirements of s390 processors. This could allow a local user to cause a denial-of-service or potentially compromise the integrity of system data.
Technical details
A vulnerability exists in the Linux kernel's s390 architecture implementation where enabling ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP (HVO) leads to architectural violations. On s390, replacing a valid page table entry with another valid entry requires a transition through an invalid state using specific instructions (like ipte or idte) to ensure TLB consistency. The HVO code lacks the necessary hooks to perform these architecture-specific detours, resulting in direct replacements that cause Translation Lookaside Buffer (TLB) entries to become stale. A local attacker could exploit this to cause reproducible system crashes or silent data corruption. The fix involves disabling the HVO optimization for the s390 architecture.
Affected products
- Linux Linux Kernel 6.2 to 6.17.7
Timeline
- 2025-10-30: patched: Initial fix commit in Linux kernel stable tree
- 2025-12-16: disclosed: CVE-2025-68179 published