UB: unaligned pointers

[cavemanloverboy]

This crate has UB.

A pointer to 32 bytes with 1-byte alignment defined here

fd_bs58/src/encode_32.rs

Line 7 in 4c66dec

let bytes: &[u8; 32] = input.as_ref().try_into().unwrap();

is cast into a slice that require 4 byte alignment on many architectures.

fd_bs58/src/encode_32.rs

Lines 20 to 26 in 4c66dec

	let bytes_as_u32: &[u32] = unsafe {
	// Cast a reference to bytes as a reference to u32
	std::slice::from_raw_parts(
	bytes.as_ptr() as *const u32,
	bytes.len() / std::mem::size_of::<u32>(),
	)
	};

The reads that follow are thus potentially unaligned.

To fix, we can change the reads from

for i in 0..BINARY_SZ_32 {
    binary[i] = bytes_as_u32[i].to_be(); // Convert to big-endian (network byte order)
}

to

for i in 0..BINARY_SZ_32 {
    unsafe {
        binary[i] = core::ptr::read_unaligned(&bytes_as_u32[i]).to_be(); // Convert to big-endian (network byte order)
    }
}