linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Jordy Zomer <jordy@pwning.systems>, linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, Mike Rapoport <rppt@linux.ibm.com>
Subject: Re: [PATCH] mm/secretmem: use refcount_t instead of atomic_t
Date: Fri, 20 Aug 2021 07:57:25 -0700	[thread overview]
Message-ID: <0874a50b61cfaf7c817cab7344c49c1641c1fd10.camel@HansenPartnership.com> (raw)
In-Reply-To: <20210820043339.2151352-1-jordy@pwning.systems>

On Fri, 2021-08-20 at 06:33 +0200, Jordy Zomer wrote:
> As you can see there's an `atomic_inc` for each `memfd` that is
> opened in the `memfd_secret` syscall. If a local attacker succeeds to
> open 2^32 memfd's, the counter will wrap around to 0. This implies
> that you may hibernate again, even though there are still regions of
> this secret memory, thereby bypassing the security check.

This isn't a possible attack, is it?  secret memory is per process and
each process usually has an open fd limit of 1024.  That's not to say
we shouldn't have overflow protection just in case, but I think today
we don't have a problem.

James



  parent reply	other threads:[~2021-08-20 14:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-20  4:33 [PATCH] mm/secretmem: use refcount_t instead of atomic_t Jordy Zomer
2021-08-20  5:33 ` Kees Cook
2021-08-24 14:05   ` Mike Rapoport
2021-10-21  9:00     ` Dmitry Vyukov
2021-08-20 14:57 ` James Bottomley [this message]
2021-08-20 16:05   ` Kees Cook
2021-08-20 16:38     ` Jordy Zomer
2021-08-20 19:40       ` James Bottomley

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=0874a50b61cfaf7c817cab7344c49c1641c1fd10.camel@HansenPartnership.com \
    --to=james.bottomley@hansenpartnership.com \
    --cc=akpm@linux-foundation.org \
    --cc=jordy@pwning.systems \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=rppt@linux.ibm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).