rAthena has heap-based buffer overflow in login server

rAthena is an open-source cross-platform massively multiplayer online role playing game (MMORPG) server. Versions prior to commit 2f5248b have a heap-based buffer overflow in the login server, remote attacker to overwrite adjacent session fields by sending a crafted `CA_SSO_LOGIN_REQ` with an oversized token length. This leads to immediate denial of service (crash) and it is possible to achieve remote code execution via heap corruption. Commit 2f5248b fixes the issue.