In the Linux kernel, the following vulnerability has been resolved: netfilter: synproxy: add mutex to guard hook reference counting As the synproxy infrastructure register netfilter hooks on-demand when a user adds the first iptables target or nftables expression, if done concurrently they can race each other. Introduce a mutex to serialize the refcount control blocks access from both frontends. While a per namespace mutex might be more efficient, it is not needed for target/expression like SYNPROXY.
https://git.kernel.org/stable/c/fbf0591275f50eae5733c3d7a8cd6c1e79933ffa
https://git.kernel.org/stable/c/debc57b83d5b323df74bf010c8d50fe26ad2ed6b
https://git.kernel.org/stable/c/aaf80701dc2f7a48fe543961e21f8ca3924d587c
https://git.kernel.org/stable/c/640441348258220e78daed40528b85b8afcedab6
https://git.kernel.org/stable/c/56ffbe3a08c01dcdb0d6adee9ce1e535bfb3b389
https://git.kernel.org/stable/c/2fcba19caaeb2a33017459d3430f057967bb91b6
https://git.kernel.org/stable/c/0f8ba5e4c53d2e4a536aa68140beda9fe59b2f88
https://git.kernel.org/stable/c/0ec9ddc1bda261a2c57636c74c8b4e53000102c9