On Fri, May 3, 2019 at 6:56 PM Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > > On Tue, Apr 30, 2019 at 03:25:06PM +0200, Andrey Konovalov wrote: > > This patch is a part of a series that extends arm64 kernel ABI to allow to > > pass tagged user pointers (with the top byte set to something else other > > than 0x00) as syscall arguments. > > > > userfaultfd_register() and userfaultfd_unregister() use provided user > > pointers for vma lookups, which can only by done with untagged pointers. > > > > Untag user pointers in these functions. > > > > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> > > --- > > fs/userfaultfd.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > > index f5de1e726356..fdee0db0e847 100644 > > --- a/fs/userfaultfd.c > > +++ b/fs/userfaultfd.c > > @@ -1325,6 +1325,9 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, > > goto out; > > } > > > > + uffdio_register.range.start = > > + untagged_addr(uffdio_register.range.start); > > + > > ret = validate_range(mm, uffdio_register.range.start, > > uffdio_register.range.len); > > if (ret) > > @@ -1514,6 +1517,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, > > if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister))) > > goto out; > > > > + uffdio_unregister.start = untagged_addr(uffdio_unregister.start); > > + > > ret = validate_range(mm, uffdio_unregister.start, > > uffdio_unregister.len); > > if (ret) > > Wouldn't it be easier to do this in validate_range()? There are a few > more calls in this file, though I didn't check whether a tagged address > would cause issues. Yes, I think it makes more sense, will do in v15, thanks! > > -- > Catalin
