leak of the vnodes

[Aurelien Jarno]

On Thu, Apr 08, 2010 at 12:58:41AM +0300, Kostik Belousov wrote:
> On Wed, Apr 07, 2010 at 11:52:56PM +0200, Aurelien Jarno wrote:
> > On Wed, Apr 07, 2010 at 11:05:28PM +0200, Petr Salinger wrote:
> > >>> What have to be logged ?
> > >> Please look at ddb command "show files", implemented in kern/kern_descrip.c,
> > >> lines 3284-3305 on HEAD. Instead of doing full dump, you can manually
> > >> inspect the output. Or, you can write some code that would search the
> > >> suspicious vnodes among the vnodes referenced from the processes
> > >> opened files. Vnode is probably leaked if use count is > 0 but no
> > >> process has vnode referenced by struct file.
> > >
> > > See attached file.
> > >
> > >>>> I think there should be something else going on.
> > >
> > > Bellow is leaking recipe tested under GNU/kFreeBSD.
> > > I would expect it leaks vnodes also under plain FreeBSD.
> > >
> > 
> > I confirm it is reproducible on plain FreeBSD. Looks like a security
> > issue, as a normal user can create a local DoS in a few dozen of
> > seconds.
> 
> I already posted the following patch in private.

Thanks, I confirm it fixes the problem, at least the testcase posted by
Petr.

> diff --git a/sys/kern/tty_pts.c b/sys/kern/tty_pts.c
> index 5cfbc71..e9dac77 100644
> --- a/sys/kern/tty_pts.c
> +++ b/sys/kern/tty_pts.c
> @@ -575,6 +575,9 @@ ptsdev_close(struct file *fp, struct thread *td)
>  	tty_lock(tp);
>  	tty_rel_gone(tp);
>  
> +	if (fp->f_vnode != NULL)
> +		return (vnops.fo_close(fp, td));
> +
>  	return (0);
>  }
> 



-- 
Aurelien Jarno	                        GPG: 1024D/F1BCDB73
aurelien at aurel32.net                 http://www.aurel32.net