{"cve":"CVE-2026-64070","nvd":{"published":"2026-07-19T16:17:47.583","modified":"2026-09-03T15:11:27.580","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/hv-gpci: fix preempt count leak in sysfs show paths\n\nFour sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb)\n(which calls preempt_disable()) but only call the matching put_cpu_var()\non the error path under the 'out:' label. Every successful read leaks\none preempt_disable():\n\n  processor_bus_topology_show()\n  processor_config_show()\n  affinity_domain_via_virtual_processor_show()\n  affinity_domain_via_domain_show()\n\n(affinity_domain_via_partition_show() was already correct.)\n\nOn a CONFIG_PREEMPT=y kernel, repeated reads raise preempt_count and\neventually return to userspace with preemption still disabled. The\nnext user-mode page fault then hits faulthandler_disabled() == 1,\ngets forced to SIGSEGV, and the resulting coredump trips\n'BUG: scheduling while atomic' in call_usermodehelper_exec ->\nwait_for_completion_state -> schedule:\n\n  BUG: scheduling while atomic: <task>/<pid>/0x00000004\n  ...\n  __schedule_bug+0x6c/0x90\n  __schedule+0x58c/0x13a0\n  schedule+0x48/0x1a0\n  schedule_timeout+0x104/0x170\n  wait_for_completion_state+0x16c/0x330\n  call_usermodehelper_exec+0x254/0x2d0\n  vfs_coredump+0x1050/0x2590\n  get_signal+0xb9c/0xc80\n  do_notify_resume+0xf8/0x470\n\nAdd an out_success label that calls put_cpu_var() before returning\nthe byte count, mirroring affinity_domain_via_partition_show().","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/45afabe7f99c5d8746434ee41c86584c01d70147","https://git.kernel.org/stable/c/903409000a07ac8e31ffedeb8516f4f8d67150c8","https://git.kernel.org/stable/c/b300312562fd6e4729697adb9f777f00ca0429f3","https://git.kernel.org/stable/c/b61ebb2826ca1852c2bbd92a676fb622c358cab4","https://git.kernel.org/stable/c/dbc30a57bd8e026995e9fa8e8c31cffd18542c01"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:45:36.895656543+00:00"},"epss":{"cve":"CVE-2026-64070","score":0.00122,"percentile":0.01961,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}