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From: Greg Kroah-Hartman <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>
Subject: Re: [PATCH v3 15/16] memcg: enable accounting for tty-related objects
Date: Thu, 22 Apr 2021 13:50:59 +0200
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To: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>
Cc: Vasily Averin <vvs-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Vladimir Davydov <vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>, Jiri Slaby <jirislaby-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>

On Thu, Apr 22, 2021 at 01:44:59PM +0200, Michal Hocko wrote:
> On Thu 22-04-21 13:23:21, Greg KH wrote:
> > On Thu, Apr 22, 2021 at 01:37:53PM +0300, Vasily Averin wrote:
> > > At each login the user forces the kernel to create a new terminal and
> > > allocate up to ~1Kb memory for the tty-related structures.
> > 
> > Does this tiny amount of memory actually matter?
> 
> The primary question is whether an untrusted user can trigger an
> unbounded amount of these allocations.

Can they?  They are not bounded by some other resource limit?

greg k-h