CVE-2019-8849: SwiftNIO SSL arbitrary code execution vulnerability

The vulnerability stems from improper stack protection mechanisms in the build configuration rather than specific functions in the source code. The advisory indicates the issue was resolved by 'signaling that an executable stack is not required,' which typically involves linker/compiler flags (e.g., -z noexecstack) rather than function-level code changes. Without access to commit diffs or patch details, we cannot identify specific vulnerable functions with high confidence. The root cause likely resides in build system configurations or assembly-level code generation that inadvertently allowed an executable stack, but no SwiftNIO SSL source code functions are explicitly implicated in the provided information.