FreeBSD: VID-30ce591c-947b-11ea-92ab-00163e433440 (CVE-2020-7454): FreeBSD -- Insufficient packet length validation in libalias

Problem Description: libalias(3) packet handlers do not properly validate the packet length before accessing the protocol headers. As a result, if a libalias(3) module does not properly validate the packet length before accessing the protocol header, it is possible for an out of bound read or write condition to occur. Impact: A malicious attacker could send specially constructed packets that exploit the lack of validation allowing the attacker to read or write memory either from the kernel (for the in-kernel NAT implementation) or from the process space for natd (for the userspace implementation).