On Tue, 2020-09-29 at 20:00 +0200, Christoph Hellwig wrote: > On Tue, Sep 29, 2020 at 10:23:50AM -0700, Linus Torvalds wrote: > > On Tue, Sep 29, 2020 at 5:16 AM Ondrej Mosnacek < > > omosnace@xxxxxxxxxx> wrote: > > > OK, so it seems that reverting comes out as the best choice here. > > > > Yeah. > > > > > BTW, I'm looking at rw_verify_area() and I see this "If (ppos)" > > > check > > > and the comment above it... And then I look at autofs_write(), > > > which > > > passes &file->f_pos, while ksys_write() passes file_ppos(file) > > > > Ok, that doesn't matter for the security_file_permission() issue, > > but > > yes, autofs is doing the traditional thing, and it's pointless. > > Using > > file_ppos(file) isn't an option since it's an inline to > > read_write.c, > > but it could just pass in NULL these days and avoid that too. > > > > So how about we just do the appended patch? Can whoever sees this > > problem just verify, even though it looks trivially correct... > > This looks sensible to me. I'd throw in a > > /* only for autofs, don't use in new code */ > > near the export, but users of these kind of functions tend to be > blind copy and paste code anyway, so the comment probably isn't > even read by the relevant parties.. I'll build a patched kernel and give it a whirl. Ian
