On Tue, Apr 28, 2020 at 08:21:24AM -0700, Darrick J. Wong wrote: > On Mon, Apr 27, 2020 at 08:19:56PM +0200, Christoph Hellwig wrote: > > access_ok just checks we are fed a proper user pointer. We also do that > > in copy_to_user itself, so no need to do this early. > > > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > > Hmm. It's a minor behavioral change that we no longer require the > entire extent array to be accessible at the start even if parts of it > would never have gotten accessed, but I don't think that matters, so: Note that access_ok only checks if the memory actually is in userspace, so they only thing seeing a behavior difference would be an exploit of some kind.
