linux-kernel - Re: CVE-2024-35840: mptcp: use OPTION_MPTCP_MPJ_SYNACK in subflow_finish

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Message-ID: <ZnBdYv9Dls8CTm0G@tiehlicka>
Date: Mon, 17 Jun 2024 17:59:30 +0200
From: Michal Hocko <mhocko@...e.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: cve@...nel.org, linux-kernel@...r.kernel.org,
	Eric Dumazet <edumazet@...gle.com>,
	linux-cve-announce@...r.kernel.org
Subject: Re: CVE-2024-35840: mptcp: use OPTION_MPTCP_MPJ_SYNACK in
 subflow_finish_connect()

On Mon 17-06-24 17:43:10, Greg KH wrote:
> On Thu, Jun 06, 2024 at 10:03:54AM +0200, Michal Hocko wrote:
> > Hi,
> > what is the actual security threat here? As far as I can see, the
> > problem that the commit requested here addresses seems to be rather
> > functional, rather than responding to an unexpected packet options with
> > a reset, we actually establish a connection with some garbage parameters
> > (likely unpredictable). Which is unfortunate but I do not see any
> > security implications.
> 
> Sorry for the delay.  I'm pretty sure this is a data leak as the
> "garbage" is coming from other kernel data, and as such, was reviewed by
> us as a vulnerability.

This is not my area so bear with me, but isn't the garbage coming from a
remote side of the connection so it is just a garbage? I would
understand that a misbehavior on the receiving end could be considered
problematic but I still do not see this happening. Or am I wrong?

-- 
Michal Hocko
SUSE Labs