GHSA-rxhx-9fj6-6h2m

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GHSA-rxhx-9fj6-6h2m

Summary: enum_map macro can cause UB when `Enum` trait is incorrectly implemented

Details: Affected versions of this crate did not properly check the length of an enum when using `enum_map!` macro, trusting user-provided length. When the `LENGTH` in the `Enum` trait does not match the array length in the `EnumArray` trait, this can result in the initialization of the enum map with uninitialized types, which in turn can allow an attacker to execute arbitrary code. This problem can only occur with a manual implementation of the Enum trait, it will never occur for enums that use `#[derive(Enum)]`. Example code that triggers this vulnerability looks like this: ```rust enum E { A, B, C, } impl Enum for E { const LENGTH: usize = 2; fn from_usize(value: usize) -> E { match value { 0 => E::A, 1 => E::B, 2 => E::C, _ => unimplemented!(), } } fn into_usize(self) -> usize { self as usize } } impl<V> EnumArray<V> for E { type Array = [V; 3]; } let _map: EnumMap<E, String> = enum_map! { _ => "Hello, world!".into() }; ``` The flaw was corrected in commit [b824e23](https://github.com/xfix/enum-map/commit/b824e232f2fb47837740070096ac253df8e80dfc) by putting `LENGTH` property on sealed trait for macro to read.

References: https://github.com/xfix/enum-map/commit/b824e232f2fb47837740070096ac253df8e80dfc, https://github.com/rustsec/advisory-db/blob/main/crates/enum-map/RUSTSEC-2022-0010.md, https://github.com/xfix/enum-map, https://github.com/xfix/enum-map/blob/master/CHANGELOG.md#version-202, https://gitlab.com/KonradBorowski/enum-map/-/blob/master/CHANGELOG.md#version-202, https://rustsec.org/advisories/RUSTSEC-2022-0010.html