{"id":"CVE-2026-64070","summary":"powerpc/hv-gpci: fix preempt count leak in sysfs show paths","details":"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 -\u003e\nwait_for_completion_state -\u003e schedule:\n\n  BUG: scheduling while atomic: \u003ctask\u003e/\u003cpid\u003e/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().","modified":"2026-07-21T03:47:53.099115666Z","published":"2026-07-19T15:39:46.536Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64070.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/903409000a07ac8e31ffedeb8516f4f8d67150c8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dbc30a57bd8e026995e9fa8e8c31cffd18542c01"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64070.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64070"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"71f1c39647d8c9d4d54a861ec81f1ff17544bcb6"},{"fixed":"903409000a07ac8e31ffedeb8516f4f8d67150c8"},{"fixed":"dbc30a57bd8e026995e9fa8e8c31cffd18542c01"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64070.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.6.0"},{"fixed":"7.0.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64070.json"}}],"schema_version":"1.7.5"}