Integer Underflow Vulnerability in Linux Kernel Affects STMMAC Implementation

CVE-2026-31649

What is CVE-2026-31649?

A vulnerability within the Linux kernel's STMMAC implementation can cause an integer underflow, leading to excessive loop iterations during packet processing. In particular, when handling jumbo frames, the calculation involving linear portion lengths versus fragment lengths can result in an unsafe value for the length variable. This vulnerability allows arbitrary kernel memory to be mapped to the DMA engine, potentially leading to kernel memory disclosure or corruption, especially in systems without IOMMU support. The introduction of safeguards, including clamping the buffer length, mitigates this risk effectively.

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