linux-kernel - Re: CVE-2023-52656: io_uring: drop any code related to SCM

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Date: Sat, 25 May 2024 17:37:22 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Jens Axboe <axboe@...nel.dk>
Cc: Gabriel Krisman Bertazi <krisman@...e.de>,
	linux-cve-announce@...r.kernel.org, cve@...nel.org,
	linux-kernel@...r.kernel.org,
	Tamás Koczka <poprdi@...gle.com>
Subject: Re: CVE-2023-52656: io_uring: drop any code related to SCM_RIGHTS

On Sat, May 25, 2024 at 09:28:35AM -0600, Jens Axboe wrote:
> On 5/25/24 9:09 AM, Eduardo' Vela" <Nava> wrote:
> > On Sat, 25 May 2024, 09:15 Greg Kroah-Hartman, <gregkh@...uxfoundation.org <mailto:gregkh@...uxfoundation.org>> wrote:
> > 
> >     On Fri, May 24, 2024 at 10:57:07AM -0600, Jens Axboe wrote:
> >     > On 5/24/24 10:45 AM, Gabriel Krisman Bertazi wrote:
> >     > > Greg Kroah-Hartman <gregkh@...uxfoundation.org <mailto:gregkh@...uxfoundation.org>> writes:
> >     > >
> >     > >> Description
> >     > >> ===========
> >     > >>
> >     > >> In the Linux kernel, the following vulnerability has been resolved:
> >     > >>
> >     > >> io_uring: drop any code related to SCM_RIGHTS
> >     > >>
> >     > >> This is dead code after we dropped support for passing io_uring fds
> >     > >> over SCM_RIGHTS, get rid of it.
> >     > >>
> >     > >> The Linux kernel CVE team has assigned CVE-2023-52656 to this issue.
> >     > >
> >     > > Hello Greg,
> >     > >
> >     > > [+Jens in Cc]
> >     > >
> >     > > This is stable material, but doesn't deserve CVE status.  There is
> >     > > nothing exploitable that is fixed here. Instead, this commit is dropping
> >     > > unreachable code after the removal of a feature, following another CVE
> >     > > report.  Doing the clean up in the original patch would have made the
> >     > > real security fix harder to review.
> >     > >
> >     > > The real issue was reported as CVE-2023-52654 and handled by a different
> >     > > commit.
> >     >
> >     > FWIW, the same is true for a number of other commits recently. They are
> >     > nowhere near CVE material, it's just generic bug fixes.
> > 
> >     Ok, glad to revoke them if you do not think they are user triggerable
> >     issues.  I'll go reject this one right now, thanks.
> > 
> > 
> > Good day!
> > 
> > So, either I'm completely lost or CVE-2023-52656 shouldn't have been
> > rejected. Forgive me for mudding the problem even more.
> > 
> > I think we need to unreject this CVE (CVE-2023-52656) or
> > CVE-2023-52654 should be amended to include the dead code removal
> > commit.. that said, that'll be weirder than just unrejecting this
> > commit.
> > 
> > The reason is that the commit "io_uring/af_unix: disable sending
> > io_uring over sockets" is not enough to fix the vulnerability in
> > stable branches, because e.g. bcedd497b3b4a0be56f3adf7c7542720eced0792
> > on 5.15 only fixes one path (io_sqe_file_register) to reach
> > unix_inflight(), but it is still reachable via another path
> > (io_sqe_fileS_register) which is only removed by
> > d909d381c3152393421403be4b6435f17a2378b4 ("io_uring: drop any code
> > related to SCM_RIGHTS").
> > 
> > Although that patch claims "it is dead code", this claim was only true
> > on upstream, but not on stable branches (or at least on 5.15 where the
> > vulnerability was proven to be reachable).
> > 
> > What a mess! ?
> 
> Ah right, yeah it was a mess because of the stable backports, it was not
> for the upstream front. Agree Greg, let's just keep it because of the
> stable side.

Now republished, thanks!

greg k-h