Re: [PATCH v2 1/4] mm: Introduce vm_uffd_ops API

Lorenzo Stoakes
2025-07-03T16:02:30Z

On Thu, Jul 03, 2025 at 11:45:40AM -0400, Peter Xu wrote:
> I still feel like we're over-worried on this. For OOT drivers I never
> cared breaking anything. For in-tree ones, this discussion can really
> happen when there's a need to. And at that time we can also have a look at
> the impl using uffd_copy(), maybe it'll not be that bad either. It seems
> to me we don't necessarily need to figure this out right now. IMHO we can
> do it two-steps in worst case.

This kind of approach in relation to f_op->mmap() is precisely how I ended
up being cc'd on an embargoed report of a critical zero-day security flaw.

So I think if anything there is under-worrying going on here.