CVE-2026-43258

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> alpha: fix user-space corruption during memory compaction<br /> <br /> Alpha systems can suffer sporadic user-space crashes and heap<br /> corruption when memory compaction is enabled.<br /> <br /> Symptoms include SIGSEGV, glibc allocator failures (e.g. "unaligned<br /> tcache chunk"), and compiler internal errors. The failures disappear<br /> when compaction is disabled or when using global TLB invalidation.<br /> <br /> The root cause is insufficient TLB shootdown during page migration.<br /> Alpha relies on ASN-based MM context rollover for instruction cache<br /> coherency, but this alone is not sufficient to prevent stale data or<br /> instruction translations from surviving migration.<br /> <br /> Fix this by introducing a migration-specific helper that combines:<br /> - MM context invalidation (ASN rollover),<br /> - immediate per-CPU TLB invalidation (TBI),<br /> - synchronous cross-CPU shootdown when required.<br /> <br /> The helper is used only by migration/compaction paths to avoid changing<br /> global TLB semantics.<br /> <br /> Additionally, update flush_tlb_other(), pte_clear(), to use<br /> READ_ONCE()/WRITE_ONCE() for correct SMP memory ordering.<br /> <br /> This fixes observed crashes on both UP and SMP Alpha systems.