Kernel-hardening archive on lore.kernel.org
 help / color / Atom feed
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Jann Horn <jannh@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	Alan Stern <stern@rowland.harvard.edu>,
	 Andrea Parri <parri.andrea@gmail.com>,
	Will Deacon <will@kernel.org>,
	 Peter Zijlstra <peterz@infradead.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	 Nicholas Piggin <npiggin@gmail.com>,
	David Howells <dhowells@redhat.com>,
	 Jade Alglave <j.alglave@ucl.ac.uk>,
	Luc Maranget <luc.maranget@inria.fr>,
	 "Paul E. McKenney" <paulmck@kernel.org>,
	Akira Yokosawa <akiyks@gmail.com>,
	 Daniel Lustig <dlustig@nvidia.com>,
	Adam Zabrocki <pi3@pi3.com.pl>,
	 kernel list <linux-kernel@vger.kernel.org>,
	 Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Oleg Nesterov <oleg@redhat.com>,
	 Andy Lutomirski <luto@amacapital.net>,
	Bernd Edlinger <bernd.edlinger@hotmail.de>,
	 Kees Cook <keescook@chromium.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	 stable <stable@vger.kernel.org>
Subject: Re: [PATCH] signal: Extend exec_id to 64bits
Date: Wed, 1 Apr 2020 16:55:42 -0700
Message-ID: <CAHk-=wgM3qZeChs_1yFt8p8ye1pOaM_cX57BZ_0+qdEPcAiaCQ@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wjz0LEi68oGJSQzZ--3JTFF+dX2yDaXDRKUpYxtBB=Zfw@mail.gmail.com>

On Wed, Apr 1, 2020 at 4:51 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> It's literally testing a sequence counter for equality. If you get
> tearing in the high bits on the write (or the read), you'd still need
> to have the low bits turn around 4G times to get a matching value.

Put another way: first you'd have to work however many weeks to do 4
billion execve() calls, and then you need to hit basically a
single-instruction race to take advantage of it.

Good luck with that. If you have that kind of God-like capability,
whoever you're attacking stands no chance in the first place.

                  Linus

  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24 21:50 Curiosity around 'exec_id' and some problems associated with it Adam Zabrocki
2020-03-29 22:43 ` Kees Cook
2020-03-30  8:34   ` Oleg Nesterov
2020-03-31  4:29   ` Adam Zabrocki
2020-04-01 20:47   ` [PATCH] signal: Extend exec_id to 64bits Eric W. Biederman
2020-04-01 20:55     ` Linus Torvalds
2020-04-01 21:03       ` Eric W. Biederman
2020-04-01 23:37     ` Jann Horn
2020-04-01 23:51       ` Linus Torvalds
2020-04-01 23:55         ` Linus Torvalds [this message]
2020-04-02  1:35           ` Jann Horn
2020-04-02  2:05             ` Linus Torvalds
2020-04-02 13:11               ` Eric W. Biederman
2020-04-02 18:06                 ` Linus Torvalds
2020-04-02  4:46     ` Jann Horn
2020-04-02 14:14       ` Eric W. Biederman
2020-04-03  2:11       ` Adam Zabrocki
2020-04-02  7:19     ` Kees Cook
2020-04-02  7:22     ` Bernd Edlinger

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='CAHk-=wgM3qZeChs_1yFt8p8ye1pOaM_cX57BZ_0+qdEPcAiaCQ@mail.gmail.com' \
    --to=torvalds@linux-foundation.org \
    --cc=akiyks@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=bernd.edlinger@hotmail.de \
    --cc=boqun.feng@gmail.com \
    --cc=dhowells@redhat.com \
    --cc=dlustig@nvidia.com \
    --cc=ebiederm@xmission.com \
    --cc=j.alglave@ucl.ac.uk \
    --cc=jannh@google.com \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luc.maranget@inria.fr \
    --cc=luto@amacapital.net \
    --cc=npiggin@gmail.com \
    --cc=oleg@redhat.com \
    --cc=parri.andrea@gmail.com \
    --cc=paulmck@kernel.org \
    --cc=peterz@infradead.org \
    --cc=pi3@pi3.com.pl \
    --cc=stable@vger.kernel.org \
    --cc=stern@rowland.harvard.edu \
    --cc=will@kernel.org \
    /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

Kernel-hardening archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kernel-hardening/0 kernel-hardening/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kernel-hardening kernel-hardening/ https://lore.kernel.org/kernel-hardening \
		kernel-hardening@lists.openwall.com
	public-inbox-index kernel-hardening

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/com.openwall.lists.kernel-hardening


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git