Excerpts from Paolo Bonzini's message of June 24, 2021 8:21 pm: > On 24/06/21 12:17, Nicholas Piggin wrote: >>> If all callers were updated that is one thing, but from the changelog >>> it sounds like that would not happen and there would be some gfn_to_pfn >>> users left over. >>> >>> But yes in the end you would either need to make gfn_to_pfn never return >>> a page found via follow_pte, or change all callers to the new way. If >>> the plan is for the latter then I guess that's fine. >> >> Actually in that case anyway I don't see the need -- the existence of >> gfn_to_pfn is enough to know it might be buggy. It can just as easily >> be grepped for as kvm_pfn_page_unwrap. > > Sure, but that would leave us with longer function names > (gfn_to_pfn_page* instead of gfn_to_pfn*). So the "safe" use is the one > that looks worse and the unsafe use is the one that looks safe. The churn isn't justified because of function name length. Choose g2pp() if you want a non-descriptive but short name. The existing name isn't good anyway because it not only looks up a pfn but also a page, and more importantly it gets a ref on the page. The name should be changed if you introduce a new API. >> And are gfn_to_page cases also >> vulernable to the same issue? > > No, they're just broken for the VM_IO|VM_PFNMAP case. No they aren't vulnerable, or they are vunlerable but also broken in other cases? Thanks, Nick
