On Mon, Apr 14, 2025 at 04:28:07PM +0200, Oleg Nesterov wrote:
> On 04/14, Oleg Nesterov wrote:
> >
> > On 04/14, Christian Brauner wrote:
> > >
> > > -static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
> > > +static int umh_coredump_setup(struct subprocess_info *info, struct cred *new)
> > > {
> > > struct file *files[2];
> > > struct coredump_params *cp = (struct coredump_params *)info->data;
> > > int err;
> > >
> > > + if (cp->pid) {
> > > + struct file *pidfs_file __free(fput) = NULL;
> > > +
> > > + pidfs_file = pidfs_alloc_file(cp->pid, 0);
> > > + if (IS_ERR(pidfs_file))
> > > + return PTR_ERR(pidfs_file);
> > > +
> > > + /*
> > > + * Usermode helpers are childen of either
> > > + * system_unbound_wq or of kthreadd. So we know that
> > > + * we're starting off with a clean file descriptor
> > > + * table. So we should always be able to use
> > > + * COREDUMP_PIDFD_NUMBER as our file descriptor value.
> > > + */
> > > + VFS_WARN_ON_ONCE((pidfs_file = fget_raw(COREDUMP_PIDFD_NUMBER)) != NULL);
> > > +
> > > + err = replace_fd(COREDUMP_PIDFD_NUMBER, pidfs_file, 0);
> > > + if (err < 0)
> > > + return err;
> >
> > Yes, but if replace_fd() succeeds we need to nullify pidfs_file
> > to avoid fput from __free(fput) ?
>
> Aah, please ignore me ;) replace_fd/do_dup2 does get_file() .
>
> For this series:
Thanks for the excellent review as usual!
