CVE-2024-26776 is a vulnerability identified in the Linux kernel specifically related to the SPI (Serial Peripheral Interface) driver for the HiSilicon SFC v3xx series (hisi-sfc-v3xx). The issue arises from the interrupt handler implementation, where the handler fails to return IRQ_NONE when no interrupt is detected. This improper handling leads to an empty interrupt scenario that triggers a null pointer dereference in the kernel, causing a crash. The kernel panic is evidenced by the error message "Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008" and a call trace involving the functions complete(), hisi_sfc_v3xx_isr(), __handle_irq_event_percpu(), and handle_irq_event(). The root cause is that the interrupt service routine (ISR) does not correctly acknowledge the absence of an interrupt, leading to dereferencing a null pointer. This vulnerability can result in a denial of service (DoS) condition due to kernel crashes. The affected versions are identified by a specific commit hash (a2ca53b52e007de81752bbb443d828f5950d6d04), indicating a particular state of the Linux kernel source code before the patch was applied. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The fix involves modifying the interrupt handler to return IRQ_NONE when no interrupt is detected, preventing the null pointer dereference and subsequent kernel panic.

For European organizations, this vulnerability poses a risk primarily in environments running Linux kernels with the affected SPI driver, especially on hardware platforms using HiSilicon SFC v3xx components. The impact is mainly a denial of service through kernel crashes, which can disrupt critical systems, servers, or embedded devices relying on this driver. Organizations in telecommunications, industrial control systems, and IoT sectors that use HiSilicon hardware or Linux-based embedded systems could be particularly affected. The disruption caused by kernel panics can lead to service outages, impacting availability and potentially causing operational downtime. While this vulnerability does not directly expose confidentiality or integrity risks, the availability impact can be significant for mission-critical infrastructure. Additionally, repeated crashes could complicate incident response and recovery efforts. Since no authentication or user interaction is required to trigger the interrupt handler, exploitation could be easier in scenarios where an attacker can induce or simulate interrupts, such as through local access or compromised peripheral devices.

To mitigate this vulnerability, European organizations should prioritize updating their Linux kernel to the patched version that includes the fix for CVE-2024-26776. Specifically, kernel maintainers and system administrators should verify that the hisi-sfc-v3xx SPI driver has been updated to return IRQ_NONE appropriately when no interrupt is detected. For embedded systems or devices where kernel updates are not immediately feasible, organizations should implement compensating controls such as restricting access to hardware interfaces that can trigger SPI interrupts, monitoring for abnormal kernel crashes, and isolating affected devices from critical networks to limit impact. Additionally, organizations should conduct thorough inventory and asset management to identify systems using the affected driver and hardware. Employing kernel crash monitoring tools and automated alerting can help detect exploitation attempts early. Collaboration with hardware vendors to obtain updated firmware or drivers that incorporate the fix is also recommended. Finally, organizations should review and test their incident response plans to handle potential denial of service incidents caused by this vulnerability.