Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode

[Al Viro]

On Tue, May 09, 2017 at 09:03:22AM -0700, Christoph Hellwig wrote:
> On Tue, May 09, 2017 at 06:02:50AM -0700, Christoph Hellwig wrote:
> > On Tue, May 09, 2017 at 06:00:01AM -0700, Andy Lutomirski wrote:
> > > fs/splice.c has some, ahem, interesting uses that have been the source
> > > of nasty exploits in the past.  Converting them to use iov_iter
> > > properly would be really, really nice.  Christoph, I don't suppose
> > > you'd like to do that?
> > 
> > I can take care of all the fs code including this one.

Oh?

> I spent the afternoon hacking up where I'd like this to head.  It's
> completely untested as of now:
> 
> 	http://git.infradead.org/users/hch/vfs.git/shortlog/refs/heads/setfs-elimination

And just what happens to driver that has no ->read_iter()?  Unless I'm
seriously misreading that, NAK with extreme prejudice.