Add advisory for sp-sized-chunks: panic-safety UAF/double-free in clear/drop_left/drop_right

crates/sp-sized-chunks/RUSTSEC-0000-0000.md

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+```toml
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "sp-sized-chunks"
+date = "2026-08-04"
+categories = ["memory-corruption"]
+keywords = ["panic-safety", "memory-safety", "use-after-free", "double-free"]
+informational = "unsound"
+
+[versions]
+patched = []
+unaffected = []
+```
+
+# Panic-safety unsoundness in `Chunk` and `InlineArray` (use-after-free / double-free)
+
+Several methods in `sp-sized-chunks` drop elements before updating the container's length/boundary metadata. If an element's `Drop` panics during the drop, the metadata update is skipped, so the container still treats the already-dropped elements as live. When the container is later dropped, its own `Drop` re-visits those slots and drops the freed elements again — a use-after-free / double-free reachable from safe Rust.
+
+`sp-sized-chunks` is a fork of `sized-chunks` (companion advisory filed separately) and carries the same bug.
+
+## Affected methods
+
+- `Chunk::clear`, `Chunk::drop_left`, `Chunk::drop_right`
+- `InlineArray::clear`
+
+## Impact
+
+- **CWE-415 (Double Free):** the same allocation is freed twice (e.g. an element holding `Box<T>`).
+- **CWE-416 (Use-After-Free):** an element reads its own freed allocation during `Drop` (e.g. `String`) — confirmed under AddressSanitizer.
+
+All are reachable from safe Rust via `catch_unwind` with element types whose `Drop` can panic.
+
+## Status
+
+The repository is archived and the crate is still on 0.1.0 with no fix. Affected users should avoid these methods with element types whose `Drop` can panic, or migrate away from the crate.