Version Information

• vyper Version (output of vyper --version OR linkable commit hash vyperlang/vyper@): b43ffac

Issue Description

In external_call.py the function _pack_arguments encodes the
arguments of the call as follow:

if len(args) != 0:
    pack_args.append(abi_encode(buf + 32, args_as_tuple, context, bufsz=buflen))

However, the buffer size passed is incorrect given that buflen is the
length of the buffer allocated at buf but here the passed buffer
starts at buf + 32.

No security implications were found for this issue.