Report various rust-xcb issues to RustSec

Closes: https://github.com/RustSec/advisory-db/issues/653

crates/xcb/RUSTSEC-0000-0000.md

@@ -0,0 +1,70 @@
+```toml
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "xcb"
+date = "2021-02-04"
+categories = ["memory-corruption", "memory-exposure"]
+
+[versions]
+patched = []
+```
+
+# Multiple soundness issues and unmaintained
+
+## Calls `std::str::from_utf8_unchecked()` without any checks
+
+The function `xcb::xproto::GetAtomNameReply::name()` calls
+`std::str::from_utf8_unchecked()` on the raw bytes that were received from the
+X11 server without any validity checks. The X11 server only prevents interior
+null bytes, but otherwise allows any X11 client to create an atom for arbitrary
+bytes.
+
+This issue is tracked here: https://github.com/rtbo/rust-xcb/issues/96
+
+## `xcb::xproto::GetPropertyReply::value()` allows arbitrary return types
+
+The function `xcb::xproto::GetPropertyReply::value()` returns a slice of type
+`T` where `T` is an unconstrained type parameter. The raw bytes received from
+the X11 server are interpreted as the requested type.
+
+The users of the `xcb` crate are advised to only call this function with the
+intended types. These are `u8`, `u16`, and `u32`.
+
+This issue is tracked here: https://github.com/rtbo/rust-xcb/issues/95
+
+## Out of bounds read in `xcb::xproto::change_property()`
+
+`xcb::xproto::change_property` has (among others) the arguments `format: u8` and
+`data: &[T]`. The intended use is one of the following cases:
+- `format = 8` and `T = u8`
+- `format = 16` and `T = u16`
+- `format = 32` and `T = u32`
+However, this constraint is not enforced. For example, it is possible to call
+the function with `format = 32` and `T = u8`. In this case, a read beyond the
+end of the `data` slice is performed and the bytes are sent to the X11 server.
+
+The users of the `xcb` crate are advised to only call this function with one of
+the intended argument combinations.
+
+This issue is tracked here: https://github.com/rtbo/rust-xcb/issues/94
+
+## 'Safe' wrapper around `std::mem::transmute()`
+
+The function `xcb::base::cast_event()` takes a reference to a
+`xcb::base::GenericEvent` and returns a reference to an arbitrary type, as
+requested by the caller (or found via type interference). The function is
+implemented as a direct call to `std::mem::transmute()`. Since the return type
+is not constrained, this allows transmution to an incorrect type or a type that
+is larger than the X11 event that was passed in.
+
+X11 events are mostly always 32 bytes large and this function works as intended.
+
+Users are advised to only cast to the event structs provided by the `xcb` crate
+(and hope for the best).
+
+This issue is tracked here: https://github.com/rtbo/rust-xcb/issues/78
+
+## xcb is unmaintained
+
+The `xcb` crate is no longer maintained by its current owner and a replacement
+is sought.