Reported

February 13, 2023

Issued

February 14, 2023

Package

cortex-m-rt (crates.io)

Type

INFO Unsound

Details

https://github.com/rust-embedded/cortex-m/discussions/469

Patched

• >=0.7.3

Unaffected

• <=0.7.0

Description

Version 0.7.1 of the cortex-m-rt crate introduced a regression causing the stack to NOT be eight-byte aligned prior to calling main (or any other specified entrypoint), violating the stack ABI of AAPCS32, the default ABI used by all Cortex-M targets. This regression is also present in version 0.7.2 of the cortex-m-rt crate.

This regression can cause certain compiler optimizations (which assume the eight-byte alignment) to produce incorrect behavior at runtime. This incorrect behavior has been observed in real-world applications.

It is advised that ALL users of v0.7.1 and v0.7.2 of the cortex-m-rt crate update to the latest version (v0.7.3), AS SOON AS POSSIBLE. Users of v0.7.0 and prior versions of cortex-m-rt are not affected by this regression.

It will be necessary to rebuild all affected firmware binaries, and flash or deploy the new firmware binaries to affected devices.