Re: [PATCH v1 2/4] clone: add CLONE_PIDFD

[Christian Brauner]

On Wed, Apr 17, 2019 at 04:22:54PM +0200, Oleg Nesterov wrote:
> On 04/16, Christian Brauner wrote:
> >
> > +	if (clone_flags & CLONE_PIDFD) {
> > +		retval = pidfd_create(pid, &pidfdf);
> > +		if (retval < 0)
> > +			goto bad_fork_free_pid;
> > +		pidfd = retval;
> > +	}
> 
> ...
> 
> > +	if (clone_flags & CLONE_PIDFD) {
> > +		fd_install(pidfd, pidfdf);
> > +		put_user(pidfd, parent_tidptr);
> 
> put_user() can fail, I don't think this error should be silently ignored,

Yes, you're right, sorry.

> this can lead to the hard-to-trigger/debug problems.
> 
> Why can't we do put_user-with-check along with pidfd_create() above?

Yes, I'll take a look where it makes sense and respin.

Christian