zerocopy: Some Ref methods are unsound with some type params

For more information:
- google/zerocopy#716
- GHSA-3mv5-343c-w2qg

Author: joshlf

crates/zerocopy/RUSTSEC-0000-0000.md

@@ -0,0 +1,31 @@
+```toml
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "zerocopy"
+date = "2023-12-14"
+url = "https://github.com/google/zerocopy/issues/716"
+keywords = ["ref", "refcell", "mutable-aliasing"]
+
+[versions]
+patched = [">= 0.2.9, < 0.3.0", ">= 0.3.2, < 0.4.0", ">= 0.4.1, < 0.5.0", ">= 0.5.2, < 0.6.0", ">= 0.6.6, < 0.7.0", ">= 0.7.31"]
+unaffected = ["< 0.2.2"]
+
+[affected.functions]
+"zerocopy::Ref::into_ref" = "*"
+"zerocopy::Ref::into_mut" = "*"
+"zerocopy::Ref::into_slice" = "*"
+"zerocopy::Ref::into_mut_slice" = "*"
+```
+
+# RustSec Advisory Template - Advisory Title Goes Here
+
+The `Ref` methods `into_ref`, `into_mut`, `into_slice`, and `into_slice_mut` are unsound
+and may allow safe code to exhibit undefined behavior when used with `Ref<B, T>` where `B`
+is [`cell::Ref`](https://doc.rust-lang.org/core/cell/struct.Ref.html) or
+[`cell::RefMut`](https://doc.rust-lang.org/core/cell/struct.RefMut.html). Note that these
+methods remain sound when used with `B` types other than `cell::Ref` or `cell::RefMut`.
+
+See https://github.com/google/zerocopy/issues/716 for a more in-depth analysis.
+
+The current plan is to yank the affected versions soon. See
+https://github.com/google/zerocopy/issues/679 for more detail.