In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix request_sock leak in sk lookup helpers

A customer reported a request_socket leak in a Calico cloud environment. We
found that a BPF program was doing a socket lookup with takes a refcnt on
the socket and that it was finding the request_socket but returning the parent
LISTEN socket via sk_to_full_sk() without decrementing the child request socket
1st, resulting in request_sock slab object leak. This patch retains the
existing behaviour of returning full socks to the caller but it also decrements
the child request_socket if one is present before doing so to prevent the leak.

Thanks to Curtis Taylor for all the help in diagnosing and testing this. And
thanks to Antoine Tenart for the reproducer and patch input.

v2 of this patch contains, refactor as per Daniel Borkmann's suggestions to
validate RCU flags on the listen socket so that it balances with bpf_sk_release()
and update comments as per Martin KaFai Lau's suggestion. One small change to
Daniels suggestion, put "sk = sk2" under "if (sk2 != sk)" to avoid an extra
instruction.

https://git.kernel.org/stable/c/3046a827316c0e55fc563b4fb78c93b9ca5c7c37

https://git.kernel.org/stable/c/516760f1d2979903eaad5b437256913c5cd98416

https://git.kernel.org/stable/c/5a62b5ba4c0ce8315b6382cd4ace81b48cd121cd

https://git.kernel.org/stable/c/8ffe2e50e9678c8373027492035f094b130437f1

https://git.kernel.org/stable/c/b03607437ea81b850599f705096b05b85e7a4a71