Reported

December 19, 2024

Issued

December 22, 2024

Package

spl-token-swap (crates.io)

Type

INFO Unsound

Keywords

#align

References

• https://github.com/solana-labs/solana-program-library/issues/5243

Patched

no patched versions

Affected Functions

Version

spl_token_swap::instruction::unpack

• <=3.0.0

Description

The library provides a safe public API unpack to cast u8 array to arbitrary types, which can cause to undefined behaviors. The length check of array can only prevent out-of-bound access on the return type. However, it can't prevent misaligned pointer when casting u8 pointer to a type aligned to larger bytes. For example, if we assign u16 to T, misaligned raw pointer dereference could happen and cause to panic. Even if we pass the type aligned to same byte as u8 (e.g., bool), it could construct a illegal type since bool can only have 0 or 1 as bit patterns, which is also an undefined behavior. The further exploits of the bug here are still not clear, so we would report this issue as unsound.

The details of PoC to reproduce undefined behavior are provided in the issue.

Advisory available under CC0-1.0 license.