Linux Kernel CVE-2026-46142

The libwx driver in the Linux kernel supports WangXun network adapters and implements SR-IOV (Single Root I/O Virtualization), which allows a single PCIe NIC to be partitioned into multiple Virtual Functions for use by VMs or containers. The WX_CFG_PORT_ST register is a PF-restricted configuration register - only the Physical Function has authority to access it. When VF initialization code incorrectly reads this register without checking whether the device is a VF or PF, the PCIe fabric treats it as an illegal register access, triggering a system hang. The correct fix is to derive the bus function ID from PCI_FUNC(pdev->devfn) when operating as a VF, bypassing the restricted register entirely. Affected CPEs are cpe:2.3:o:linux:linux_kernel across multiple stable branches including 6.6.x, 6.12.x, 6.17.x/6.18.x, and 7.0.x/7.1-rc. No CWE is formally assigned, but the root cause class is an improper authorization or missing context check on hardware register access during device role differentiation.