IPFS go-bitfield vulnerable to DoS via malformed size arguments

Impact

When feeding untrusted user input into the size parameter of NewBitfield and FromBytes functions, an attacker can trigger panics.

This happen when the size is a not a multiple of 8 or is negative.
There were already a note in the NewBitfield documentation:
> ```
> Panics if size is not a multiple of 8.
> ````

But it incomplete and missing from FromBytes’s documentation.

This has been replaced by returning an (Bitfield, error) and returning a non nil error if the size is wrong.

Patches

• https://github.com/ipfs/go-bitfield/commit/5e1d256fe043fc4163343ccca83862c69c52e579

Workarounds

• Ensure size%8 == 0 && size >= 0 yourself before calling NewBitfield or FromBytes

References

• https://github.com/ipfs/go-unixfs/security/advisories/GHSA-q264-w97q-q778