Add unsoundness in os_socketaddr (#1384)

crates/os_socketaddr/RUSTSEC-0000-0000.md

@@ -0,0 +1,25 @@
+```toml
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "os_socketaddr"
+date = "2022-08-26"
+url = "https://github.com/a-ba/os_socketaddr/issues/3"
+categories = ["memory-corruption"]
+keywords = ["memory", "layout", "cast"]
+informational = "unsound"
+
+[versions]
+patched = [">= 0.2.2"]
+```
+
+# `os_socketaddr` invalidly assumes the memory layout of std::net::SocketAddr
+
+The [`os_socketaddr`](https://crates.io/crates/os_socketaddr) crate has assumed
+`std::net::SocketAddrV4` and `std::net::SocketAddrV6` have the same memory layout as the system C
+representation `sockaddr`. It has simply casted the pointers to convert the socket addresses to the
+system representation.
+
+These layout were [changed into idiomatic rust types](https://github.com/rust-lang/rust/pull/78802)
+in nightly `std`. Starting from rustc 1.64 the affected versions of this crate will have undefined
+behaviour.
+