CVE-2026-80611
Received Received - Intake

ACPI LPI Enter Functions Marked as __cpuidle in Linux Kernel

Publication date: 2026-08-28

Last updated on: 2026-08-28

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: ACPI: processor_idle: Mark LPI enter functions as __cpuidle When function tracing or Kprobes is enabled, entering an ACPI Low Power Idle (LPI) state triggers the following RCU splat: RCU not on for: acpi_idle_lpi_enter+0x4/0xd8 WARNING: CPU: 8 PID: 0 at include/linux/trace_recursion.h:162 function_trace_call+0x1e8/0x228 The acpi_idle_lpi_enter() function is invoked within the cpuidle path after RCU has already been disabled for the current local CPU. Consequently, ftrace's function_trace_call() expects RCU to be actively watching before recording trace data, emitting a warning if it is not. Fix this by annotating acpi_idle_lpi_enter(), the generic __weak stub, and the RISC-V implementation of acpi_processor_ffh_lpi_enter() with __cpuidle. This moves these functions into the '.cpuidle.text' section, implicitly disabling ftrace instrumentation (notrace) along this sensitive path and preventing trace-induced RCU warnings during idle entry.

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Meta Information

Published
2026-08-28
Last Modified
2026-08-28
Generated
2026-09-17
AI Q&A
2026-08-28
EPSS Evaluated
2026-09-15
NVD
CVE-2026-80611
EUVD
EUVD-2026-67487

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability involves a kernel warning triggered when entering ACPI Low Power Idle (LPI) states with function tracing or Kprobes enabled. The issue occurs because the acpi_idle_lpi_enter() function runs after RCU is disabled, causing ftrace to emit an RCU splat warning. The fix annotates related functions with __cpuidle to move them into a section that disables ftrace instrumentation, preventing the warning.

Detection Guidance

This vulnerability is specific to the Linux kernel's ACPI processor idle handling and may manifest as RCU splats in kernel logs when function tracing or Kprobes is enabled. Check kernel logs for messages like 'RCU not on for: acpi_idle_lpi_enter' or 'WARNING: CPU: ... PID: 0 at include/linux/trace_recursion.h:162 function_trace_call+0x1e8/0x228'.

Impact Analysis

This vulnerability primarily impacts systems using ACPI Low Power Idle states with kernel tracing tools enabled. It causes kernel warnings during idle entry but does not directly affect functionality or security. The warnings may clutter logs and indicate potential instability in idle state handling.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It is a Linux kernel issue related to ACPI idle state handling and RCU warnings during CPU idle entry, which does not involve data privacy, security controls, or protected health information.

Mitigation Strategies

Apply the kernel patch that annotates acpi_idle_lpi_enter() and related functions with __cpuidle. This moves them into the '.cpuidle.text' section, disabling ftrace instrumentation on this path. Update to a fixed kernel version if available.

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