CVE-2026-74309 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
Look up the IRQ index in oct_hw->irqs instead of assuming irq - irqs[0]. This supports non-contiguous IRQ numbers and
avoids incorrect ring indexing when irqs[0] is not the base.
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability exists within the Linux kernel's virtual data path acceleration implementation, specifically affecting the octeon_ep driver component that handles VDPA (Virtual Data Path Acceleration) operations. The issue stems from an improper assumption in the interrupt handling mechanism where the system incorrectly maps interrupt requests to hardware rings by directly calculating the IRQ index as irq - irqs[0] without proper validation against the actual hardware IRQ mapping structure.
The technical flaw manifests when the kernel processes interrupt events for VDPA devices, particularly those utilizing the Octeon hardware platform. The driver maintains an array of hardware IRQs in oct_hw->irqs which contains the actual IRQ assignments for the device. However, the interrupt handler routine was designed to assume that irqs[0] represents the base interrupt number, leading to incorrect ring indexing when IRQ numbers are not contiguous or when the first IRQ in the array does not correspond to the expected base value. This misalignment occurs because the code fails to properly look up the actual IRQ index within the oct_hw->irqs array structure before performing the ring mapping operation.
The operational impact of this vulnerability can be severe for systems utilizing VDPA acceleration, particularly those running high-performance network workloads or virtualized environments where interrupt handling efficiency is critical. When incorrect IRQ-to-ring mapping occurs, it can result in packets being directed to wrong hardware rings, causing data corruption, packet loss, or complete network service disruption. The vulnerability affects systems where the kernel's VDPA framework is actively managing Octeon-based network devices, potentially leading to denial of service conditions or compromised network performance that could be exploited by malicious actors to disrupt network operations.
The root cause aligns with CWE-129, which addresses improper validation of array indices, and specifically relates to improper index calculation in interrupt handling routines. This vulnerability also maps to ATT&CK technique T1059 by potentially allowing an attacker to manipulate interrupt processing paths or T1499 by causing service disruption through network packet handling failures. The fix implemented resolves this issue by modifying the interrupt handler to properly traverse the oct_hw->irqs array structure to determine the correct IRQ index rather than relying on the incorrect assumption about irqs[0] serving as the base interrupt number.
Mitigation strategies should focus on applying the kernel patch that correctly implements the IRQ lookup mechanism in the interrupt handler routine. System administrators should prioritize updating their Linux kernel versions to include this fix, particularly in production environments running VDPA-accelerated network services or virtualization platforms. Monitoring for unusual network packet loss patterns or interrupt handling anomalies could help identify systems affected by this vulnerability before exploitation occurs, while also ensuring that proper testing is conducted on patched systems to verify the integrity of the interrupt mapping functionality.
The fix demonstrates proper defensive programming practices by validating array indices against expected hardware structures rather than making assumptions about memory layout. This approach aligns with security best practices for kernel development and helps prevent similar issues in other interrupt handling components. Organizations should also consider implementing automated patch management processes to ensure timely deployment of security fixes, particularly for critical kernel subsystems that handle network interrupts and virtualization acceleration features.