Generally speaking, Linux doesn't suffer from ELF-executable-file-infecting viruses in practice, because most random executables aren't run with root permissions, so they don't have permission to write to widely-executed executables, which you install from the package system.
However, anything in the build toolchain that someone uses to build those widely-executed executables necessarily does have permission to write to them!
This is certainly not novel, having been the subject of a Turing Award speech, but it is something that many people haven't thought through.
