GitHub Advisoryadvisory · crates.io

GHSA-83gg-pwxf-jr89 `array!` macro is unsound in presence of traits that implement methods it calls internally

MEDIUM Published 2022-06-16 Modified 2022-06-20 Official page ↗
Ecosystem
crates.io
Packages
array-macro
Severity
Moderate
Reviewed
2022-06-16

Affected packages

• crates.io array-macro: >= 0.1.2, < 1.0.5 → fixed in 1.0.5

Description

Affected versions of this crate called some methods using auto-ref. The affected code looked like this. ```rust let mut arr = $crate::__core::mem::MaybeUninit::uninit(); let mut vec = $crate::__ArrayVec::::new(arr.as_mut_ptr() as *mut T); ``` In this case, the problem is that `as_mut_ptr` is a method of `&mut MaybeUninit`, not `MaybeUninit`. This made it possible for traits to hijack the method calls in order to cause unsoundness. ```rust trait AsMutPtr { fn as_mut_ptr(&self) -> *mut T; } impl AsMutPtr for std::mem::MaybeUninit { fn as_mut_ptr(&self) -> *mut T { std::ptr::null_mut() } } array![0; 1]; ``` The flaw was corrected by explicitly referencing variables in macro body in order to avoid auto-ref.

References