Unsoundness in opt-in ARMv8 assembly backend for `keccak`
Low severity
GitHub Reviewed
Published
Feb 19, 2026
to the GitHub Advisory Database
•
Updated Feb 19, 2026
Description
Published to the GitHub Advisory Database
Feb 19, 2026
Reviewed
Feb 19, 2026
Last updated
Feb 19, 2026
Summary
The
asm!block enabled by the off-by-defaultasmfeature, when enabled on ARMv8 targets, misspecified the operandtype for all of its operands, using
infor pointers and values which were subsequently mutated by operations performedwithin the assembly block.
Impact
It's unclear what practical impact, if any, this actually had. Incorrect operand types are technically undefined
behavior, however changing them had no actual impact on the generated assembly for these targets. The possibility still
exists that it may lead to potential memory safety or other issues on hypothetical future versions of rustc.
Mitigation
The operand types were changed from
intoinout, and the impacted versions of thekeccakcrate were yanked.References