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Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-64070

Linux Linux — powerpc/hv-gpci: fix preempt count leak in sysfs show paths
  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   L   L   L   N  U  N  N  H    5.5   .0016    4.7     —
AFFECTED
  Product  Versions                                    Fixed
  Linux    71f1c39647d8c9d4d54a861ec81f1ff17544bcb6 –  —
  Linux    6.6 –                                       6.6.156
TIMELINE
  Jul 19  Reserved by Linux
  Jul 19  Published (CNA: Linux)
  Sep 3   ENRICHED — CVE-2026-64070 (Linux). Received CVSS 5.5 and CPE data from NVD.
CNA: Linux · CVSS v3.1 · 5 references · NVD status: Analyzed

Description

In the Linux kernel, the following vulnerability has been resolved: powerpc/hv-gpci: fix preempt count leak in sysfs show paths Four sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb) (which calls preempt_disable()) but only call the matching put_cpu_var() on the error path under the 'out:' label. Every successful read leaks one preempt_disable(): processor_bus_topology_show() processor_config_show() affinity_domain_via_virtual_processor_show() affinity_domain_via_domain_show() (affinity_domain_via_partition_show() was already correct.) On a CONFIG_PREEMPT=y kernel, repeated reads raise preempt_count and eventually return to userspace with preemption still disabled. The next user-mode page fault then hits faulthandler_disabled() == 1, gets forced to SIGSEGV, and the resulting coredump trips 'BUG: scheduling while atomic' in call_usermodehelper_exec -> wait_for_completion_state -> schedule: BUG: scheduling while atomic: <task>/<pid>/0x00000004 ... __schedule_bug+0x6c/0x90 __schedule+0x58c/0x13a0 schedule+0x48/0x1a0 schedule_timeout+0x104/0x170 wait_for_completion_state+0x16c/0x330 call_usermodehelper_exec+0x254/0x2d0 vfs_coredump+0x1050/0x2590 get_signal+0xb9c/0xc80 do_notify_resume+0xf8/0x470 Add an out_success label that calls put_cpu_var() before returning the byte count, mirroring affinity_domain_via_partition_show().

Lifecycle

Complete event history — 3 events, chronological
DateEventDetail
July 19, 2026ReservedReserved by Linux
July 19, 2026PublishedPublished (CNA: Linux)
September 3, 2026ENRICHEDENRICHED — CVE-2026-64070 (Linux). Received CVSS 5.5 and CPE data from NVD.

Affected

Affected products and packages — 2 rows
VendorProduct / PackageEcosystemVersion introducedFixed
LinuxLinux—71f1c39647d8c9d4d54a861ec81f1ff17544bcb6—
LinuxLinux—6.66.6.156

References (5)

Related

Authoritative record: CVE-2026-64070 at cve.org

Vendors: linux

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-64070 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.