Not really sure how much of this is still true. Since cloud services and locked devices took over most of the software that people use, it doesn't come up much anymore.
Interesting question and answer, thanks for the link. To save others a click / searching for the relevant parts, these seem to be it:
> since it's not copyright infringement for you to apply a patch, it's also not copyright infringement for someone to give you a patch.
> For example, Galoob's Game Genie, which patches the software in Nintendo cartridges, does not infringe Nintendo's copyrights. ``Having paid Nintendo a fair return, the consumer may experiment with the product and create new variations of play, for personal enjoyment, without creating a derivative work.''
For the EU, merely this is said:
> The European Software Directive (adopted by the UK in 1992) gives users the freedom to copy, run, modify, and reverse-engineer lawfully acquired programs.
Given the reasoning "if it's not copyright infringement to patch, it's also not infringement to give you a patch", which I honestly don't quite follow, this ought to mean that the law works the same way in the EU. (The reason I don't follow that logic is that copyright doesn't dictate what I can do with information I already have: it's about distribution as far as I know. So of course it's okay for me to apply a patch when not considering any law other than copyright (at least from my not-a-lawyer and European perspective), but that doesn't mean I can make what might perhaps be argued to be a derivative work and spread that around.)
Not really sure how much of this is still true. Since cloud services and locked devices took over most of the software that people use, it doesn't come up much anymore.