Linux Kernel CVE-2026-31737

The ftgmac100 is a Faraday-based Gigabit Ethernet MAC controller driver integrated into the Linux kernel networking subsystem. The vulnerability exists in the multi-stage memory allocation routine ftgmac100_alloc_rings(), which sequentially allocates socket buffers (rx_skbs, tx_skbs), DMA descriptor rings (rxdes, txdes), and scratch buffers (rx_scratch) for Ethernet frame transmission and reception. The driver uses this function during device open operations to prepare packet handling infrastructure. The root cause is insufficient error handling: when intermediate allocations fail, the function returns -ENOMEM immediately without executing proper unwinding logic to release resources allocated in earlier stages. This is a resource leak rather than memory corruption, but persistent failures during driver initialization can exhaust kernel memory pools. The issue was fixed by implementing staged local unwind labels that follow standard Linux netdev driver cleanup patterns, ensuring all partially-allocated resources are freed in reverse allocation order.