5.15.223 (longterm, Branch 5.15)

Linux kernel 5.15.223 (longterm) delivered a focused set of networking fixes, with particular attention to IPv4 and netfilter stability and security. Among the most relevant fixes were the deferred freeing of inet_opt and ireq_opt structures until after an RCU grace period to prevent use-after-free conditions, and the validation of checksum_start before completing checksum operations to avoid potential memory corruption or crashes. Additionally, a regression in netfilter's nfnetlink_queue was addressed to restore proper SCTP traffic handling that had been broken in prior updates. Overall, this release emphasized hardening core networking code against memory-safety issues and correcting a protocol-specific regression.