In the Linux kernel, the following vulnerability has been resolved:
selinux: avoid sk_socket dereference in selinux_sctp_bind_connect()
selinux_sctp_bind_connect() dereferences sk->sk_socket to pass a struct socket * to selinux_socket_bind() and selinux_socket_connect_helper(). However, when the hook is invoked from the ASCONF softirq path (sctp_process_asconf), there is no file reference guaranteeing that sk->sk_socket is non-NULL. The setsockopt callers (bindx, connectx, set_primary, sendmsg connect) hold a file reference and are not affected.
Both selinux_socket_bind() and selinux_socket_connect_helper() immediately resolve sock->sk, never using the struct socket * for anything else. Refactor the inner logic into helpers that take a struct sock * directly so that selinux_sctp_bind_connect() never needs to touch sk->sk_socket at all.
References
- https://git.kernel.org/stable/c/37d642b37ccdc31e1947c2ebc8dc38f03d4a0ceb
- https://git.kernel.org/stable/c/56acfeb10019e200ab6787d01f8d7cbe0f01526f
- https://git.kernel.org/stable/c/5d4d93f9bfbc997ffbb03cd6107e8f6979dbb9b4
- https://git.kernel.org/stable/c/cc8bd47b35eca82393cbad08b1cc86f02e034439
- https://git.kernel.org/stable/c/d61a80b17254be7230bc5544f8e62ddf21ab38e2