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

[Christoph Hellwig]

On Wed, May 10, 2017 at 04:39:12AM +0100, Al Viro wrote:
> fcntl stuff: I've decided not to put something similar into work.compat
> since I couldn't decide what to do with compat stuff - word-by-word copy
> from userland converting to struct flock + conversion to posix_lock +
> actual work + conversion to flock + word-by-word copy to userland...  Smells
> like we might be better off with compat_flock_to_posix_lock() et.al.
> I'm still not sure; played a bit one way and another and dediced to drop
> it for now.  Hell knows...

My version already is an improvement in lines of code alone.  Between
that and stopping to mess with the address limit I think it's a clear
winner.  But it's pretty independent of the rest, and I'll just run
it through Jeff and Bruce and ask them what they think.