RUSTSEC-2020-0073

Mutable reference with immutable provenance

Issued
Package
image (crates.io)
Type
Unsound
Aliases
Details
https://github.com/image-rs/image/issues/1357
Patched
  • >=0.23.12
Keywords
  • pointer
  • cast
  • provenance
Affected Functions
Version
image::Bgr::from_slice_mut
  • <0.23.12
image::Bgra::from_slice_mut
  • <0.23.12
image::Luma::from_slice_mut
  • <0.23.12
image::LumaA::from_slice_mut
  • <0.23.12
image::Rgb::from_slice_mut
  • <0.23.12
image::Rgba::from_slice_mut
  • <0.23.12

Description

A mutable reference to a struct was constructed by dereferencing a pointer obtained from slice::as_ptr. Instead, slice::as_mut_ptr should have been called on the mutable slice argument. The former performs an implicit reborrow as an immutable shared reference which does not allow writing through the derived pointer.

There is no evidence for miscompilation, exploitable or otherwise, caused by this bug. Further investigation on Zulip suggests that the unoptimized generated LLVM IR does not contain any UB itself, effectively mitigating further effects.

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