CVE-2024-46750 is a vulnerability identified in the Linux kernel's PCI subsystem, specifically related to the locking mechanisms used during PCI bus resets. The issue arises from missing locking of the PCI bridge device during the pci_bus_lock() operation. The vulnerability was discovered through lock dependency (lockdep) analysis, which revealed that the pci_bridge_secondary_bus_reset function triggers secondary bus resets without properly locking the bridge device. While pci_bus_reset() uses pci_bus_lock() to lock the bus before reset, this lock does not cover the bridge device itself, leading to potential race conditions or deadlocks. The fix involves adding pci_dev_lock() calls for the bridge device (bus->self) to the pci_bus_lock() procedure, ensuring that the bridge is properly locked during reset operations. This change prevents recursive locking deadlocks and improves the stability and correctness of PCI bus reset sequences. The vulnerability affects Linux kernel versions identified by the commit hash 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and was published on September 18, 2024. No known exploits are reported in the wild at this time, and no CVSS score has been assigned yet. The vulnerability is technical and low-level, related to kernel synchronization primitives in PCI device management.

For European organizations, this vulnerability primarily affects systems running vulnerable Linux kernel versions that manage PCI devices, including servers, workstations, and embedded systems. Potential impacts include system instability, kernel panics, or deadlocks during PCI bus reset operations, which could lead to temporary denial of service or degraded system performance. In environments with high PCI device usage, such as data centers, telecommunications infrastructure, or industrial control systems, this could disrupt critical operations. Although there is no evidence of remote code execution or privilege escalation directly linked to this vulnerability, the risk of system crashes or hangs could impact availability and operational continuity. Organizations relying on Linux-based infrastructure for critical services should be aware of this issue, especially if they use hardware configurations with complex PCI topologies or virtualized environments where PCI device resets are frequent. The absence of known exploits reduces immediate risk, but unpatched systems remain vulnerable to potential future exploitation or stability issues.

European organizations should prioritize updating their Linux kernels to versions that include the patch for CVE-2024-46750 as soon as they become available from their Linux distribution vendors. Since the vulnerability relates to kernel-level locking, applying official kernel updates or backported patches is the most effective mitigation. System administrators should audit their PCI device configurations and monitor kernel logs for warnings related to pci_bridge_secondary_bus_reset or pci_reset_bus functions, which may indicate attempts to trigger the vulnerability or system instability. For critical systems, consider implementing kernel live patching solutions to minimize downtime during updates. Additionally, organizations should test kernel updates in staging environments to ensure compatibility with their hardware and workloads, particularly for systems with complex PCI device arrangements. Maintaining robust backup and recovery procedures will help mitigate potential availability impacts. Finally, monitoring vendor advisories and security bulletins for updates on this vulnerability and any emerging exploit reports is recommended.