kernel input validation

The kernel input validation tag covers discussions about how the Linux kernel checks and sanitizes data coming from userspace or external sources. A recent thread highlights a security fix in the RDMA umad path where ib_umad_write() now rejects negative data_len values, preventing potential memory-safety bugs. Such validation is critical in kernel code, especially in interfaces like umad that sit close to privileged kernel plumbing and high-performance networking. The tag focuses on concrete validation checks that separate harmless input from serious reliability or security issues, with an emphasis on kernel-level input handling in Windows and Linux systems.