In the Linux kernel, the following vulnerability has been resolved: powerpc/hv-gpci: fix preempt count leak in sysfs show paths Four sysfs show()… (CVE-2026-64070)
A vulnerability in the Linux kernel's powerpc/hv-gpci subsystem caused a preempt count leak in four sysfs show() callbacks. This leak occurs because put_cpu_var() is only called on error paths, leading to preemption remaining disabled after successful reads. On kernels with CONFIG_PREEMPT=y, repeated reads can cause preemption to stay disabled, resulting in a SIGSEGV and a kernel BUG triggered by scheduling while atomic. The issue has been fixed by adding a call to put_cpu_var() on successful paths.
AI Analysis
Technical Summary
The Linux kernel vulnerability CVE-2026-64070 involves a preempt count leak in four sysfs show() callbacks within the powerpc/hv-gpci driver. These callbacks call get_cpu_var(hv_gpci_reqb), which disables preemption, but only call put_cpu_var() on error paths, causing preemption to remain disabled after successful reads. This leads to an increased preempt_count and eventually causes a user-mode page fault with preemption disabled, triggering a SIGSEGV and a kernel BUG due to scheduling while atomic. The fix involves adding an out_success label that calls put_cpu_var() before returning, mirroring the correct behavior in affinity_domain_via_partition_show().
Potential Impact
On affected Linux kernels with CONFIG_PREEMPT=y, repeated reads of the affected sysfs entries cause preemption to remain disabled, leading to a user-mode page fault and a forced SIGSEGV. This results in a kernel BUG related to scheduling while atomic, potentially causing system instability or crashes during coredump handling.
Mitigation Recommendations
A fix has been implemented in the Linux kernel source to address this vulnerability by ensuring put_cpu_var() is called on all return paths in the affected sysfs show() callbacks. Users should update to the fixed kernel version once available. Patch status is not yet confirmed in this data; check the official Linux kernel advisories or vendor updates for the current remediation guidance.
In the Linux kernel, the following vulnerability has been resolved: powerpc/hv-gpci: fix preempt count leak in sysfs show paths Four sysfs show()… (CVE-2026-64070)
Description
A vulnerability in the Linux kernel's powerpc/hv-gpci subsystem caused a preempt count leak in four sysfs show() callbacks. This leak occurs because put_cpu_var() is only called on error paths, leading to preemption remaining disabled after successful reads. On kernels with CONFIG_PREEMPT=y, repeated reads can cause preemption to stay disabled, resulting in a SIGSEGV and a kernel BUG triggered by scheduling while atomic. The issue has been fixed by adding a call to put_cpu_var() on successful paths.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel vulnerability CVE-2026-64070 involves a preempt count leak in four sysfs show() callbacks within the powerpc/hv-gpci driver. These callbacks call get_cpu_var(hv_gpci_reqb), which disables preemption, but only call put_cpu_var() on error paths, causing preemption to remain disabled after successful reads. This leads to an increased preempt_count and eventually causes a user-mode page fault with preemption disabled, triggering a SIGSEGV and a kernel BUG due to scheduling while atomic. The fix involves adding an out_success label that calls put_cpu_var() before returning, mirroring the correct behavior in affinity_domain_via_partition_show().
Potential Impact
On affected Linux kernels with CONFIG_PREEMPT=y, repeated reads of the affected sysfs entries cause preemption to remain disabled, leading to a user-mode page fault and a forced SIGSEGV. This results in a kernel BUG related to scheduling while atomic, potentially causing system instability or crashes during coredump handling.
Mitigation Recommendations
A fix has been implemented in the Linux kernel source to address this vulnerability by ensuring put_cpu_var() is called on all return paths in the affected sysfs show() callbacks. Users should update to the fixed kernel version once available. Patch status is not yet confirmed in this data; check the official Linux kernel advisories or vendor updates for the current remediation guidance.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-h8p2-7w9q-6g4f
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-64070"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a5d27a92a4a8d598912c235
Added to database: 07/19/2026, 19:38:17 UTC
Last enriched: 07/19/2026, 19:52:15 UTC
Last updated: 07/20/2026, 17:26:47 UTC
Views: 11
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