CVE-2026-93254
Received Received - Intake

Kernel Exit Preemption Optimization in Linux

Publication date: 2026-09-24

Last updated on: 2026-09-24

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: arm64: entry: Avoid unnecessary local_irq_disable() on kernel exit Currently, when exiting to kernel mode, we attempt involuntary preemption. The preemption logic expects IRQs to be disabled, which is why we call local_irq_disable() before attempting preemption. However, depending on the context, local_irq_disable() may be unnecessary: - __el1_irq(), the non-NMI EL1 IRQ path, already has IRQs disabled, so local_irq_disable() is redundant. - irqentry_exit_to_kernel_mode_preempt() immediately returns when exiting from an NMI-like context, so calling local_irq_disable() beforehand is unnecessary work. Furthermore, it confuses the pNMI state tracking when we are in a context with interrupts disabled and the GIC_PRIO_PSR_I_SET bit is set in the PMR, leading to a warning when CONFIG_ARM64_DEBUG_PRIORITY_MASKING=y: WARNING: ./arch/arm64/include/asm/irqflags.h:63 at arm64_exit_to_kernel_mode+0xb8/0xc0, CPU#40: retsnoop/31805 CPU: 40 UID: 0 PID: 31805 Comm: retsnoop Not tainted 7.2.0-rc6-next-20260805 #7 PREEMPTLAZY pstate: 234013c9 (nzCv DAIF +PAN -UAO +TCO +DIT +SSBS BTYPE=--) pc : arm64_exit_to_kernel_mode (arch/arm64/kernel/entry-common.c:63) lr : el1_abort (arch/arm64/kernel/entry-common.c:323) pmr: 000000f0 Call trace: arm64_exit_to_kernel_mode (arch/arm64/kernel/entry-common.c:63) (P) el1_abort (arch/arm64/kernel/entry-common.c:323) el1h_64_sync_handler (arch/arm64/kernel/entry-common.c:449) el1h_64_sync (arch/arm64/kernel/entry.S:589) [...] Split arm64_exit_to_kernel_mode() into preempt, non-preempt, and dispatch parts so that we can avoid this extra work where it is not needed and avoid breaking the pNMI tracking logic.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-09-24
Last Modified
2026-09-24
Generated
2026-09-24
AI Q&A
2026-09-24
EPSS Evaluated
N/A
NVD
CVE-2026-93254
EUVD
EUVD-2026-86126

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel 7.2.0-rc6-next-20260805

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This vulnerability in the Linux kernel involves unnecessary calls to local_irq_disable() when exiting to kernel mode, which can cause issues with pNMI state tracking and trigger warnings when CONFIG_ARM64_DEBUG_PRIORITY_MASKING is enabled.

Detection Guidance

This vulnerability is specific to the Linux kernel's arm64 architecture and does not have a direct detection method via network or system commands. It is resolved by applying the kernel patch that splits arm64_exit_to_kernel_mode(). Check your kernel version and compare it against the patched version to confirm if the fix is applied.

Impact Analysis

The impact includes potential system warnings and confusion in interrupt handling, particularly on arm64 systems with specific kernel configurations. It may affect system stability and debugging processes.

Mitigation Strategies

Apply the latest kernel patch provided by your Linux distribution that includes the fix for this vulnerability. Reboot your system after applying the patch to ensure the updated kernel is active. Monitor kernel logs for any related warnings if CONFIG_ARM64_DEBUG_PRIORITY_MASKING is enabled.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-93254. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart