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From:   Kuniyuki Iwashima <kuniyu@amazon.com>
To:     <lmb@isovalent.com>
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        <davem@davemloft.net>, <edumazet@google.com>, <kuba@kernel.org>,
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        <martin.lau@kernel.org>, <martin.lau@linux.dev>,
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Subject: Re: [PATCH bpf-next] net: Fix slab-out-of-bounds in inet[6]_steal_sock
Date:   Wed, 9 Aug 2023 10:14:51 -0700
Message-ID: <20230809171451.78725-1-kuniyu@amazon.com>
In-Reply-To: <CAN+4W8h44UdLRT+QLdh2rNeiKg0AkPAuGtYuXOgtFzvT2kHsWg@mail.gmail.com>
References: <CAN+4W8h44UdLRT+QLdh2rNeiKg0AkPAuGtYuXOgtFzvT2kHsWg@mail.gmail.com>
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From: Lorenz Bauer <lmb@isovalent.com>
Date: Wed, 9 Aug 2023 17:55:02 +0100
> On Wed, Aug 9, 2023 at 4:56 PM Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
> >
> > > Things we could do if necessary:
> > > 1. Reset the flag in inet_csk_clone_lock like we do for SOCK_RCU_FREE
> >
> > I think we can't do this as sk_reuseport is inherited to twsk and used
> > in inet_bind_conflict().
> 
> Ok, so what kind of state does reuseport carry in the various states then?
> 
> TCP_LISTEN: sk_reuseport && sk_reuseport_cb
> TCP_ESTABLISHED: sk_reuseport && !sk_reuseport_cb
> TCP_TIME_WAIT: sk_reuseport && !sk_reuseport_cb
> 
> Where is sk_reuseport_cb cleared? On clone? Or not at all?

sk_clone_lock() does when cloning sk from listener, and we
cannot check sk_reuseport_cb for twsk as it doesn't have the
member.


> 
> > > 2. Duplicate the cb check into inet[6]_steal_sock
> >
> > or 3. Add sk_fullsock() test ?
> 
> I guess this would be in addition to the convoluted series of checks
> I've removed in this patch?

Yes.