CVE Catalog

CVE-2026-64070

Low risk· EPSS 5%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.16%

5th percentile - higher than 5% of all known CVEs

Summary

In the Linux kernel powerpc/hv-gpci subsystem, a preempt count leak was found in four sysfs show() functions. These functions call preempt_disable() via get_cpu_var() but fail to call put_cpu_var() on successful reads, causing the preempt counter to accumulate. After repeated reads, the kernel may return to userspace with preemption disabled, leading to SIGSEGV and 'BUG: scheduling while atomic' errors.

Risk Assessment

The organization risks system crashes, kernel bugs, and disrupted user processes, potentially causing data loss or service unavailability. The vulnerability can be exploited locally to trigger a 'scheduling while atomic' state, destabilizing the system.

Recommendation

Immediately update the Linux kernel to a version containing the fix (commit adding out_success label with put_cpu_var()). For production systems, apply the security patch from your distributor.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

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().

Vulnerability data from NVD (NIST) · CISA KEV · EPSS