Re: [PATCH 3/4] devpts: Make the newinstance option historical

From: Al Viro
Date: Sun Sep 23 2012 - 02:34:44 EST


On Sun, Sep 23, 2012 at 07:30:38AM +0100, Al Viro wrote:
> On Sat, Sep 22, 2012 at 10:59:04PM -0700, Eric W. Biederman wrote:
>
> > The test:
> > >> + if (filp->f_vfsmnt->mnt_root == filp->f_dentry)
> > kicks in and no redirection is performed.
>
> Umm... OK, after the first round of recursion. Unless you bind /something/pts
> on /something.

Other way round, of course... E.g.
mount --bind /dev /dev/pts
mount --bind /dev /dev/pts/pts
etc. enough times to overflow the kernel stack on recursion.
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