From: Eric Dumazet <eric.dumazet@gmail.com>
To: Dave Jones <davej@redhat.com>
Cc: netdev@vger.kernel.org, Matthew Daley <mattjd@gmail.com>
Subject: Re: Fix NULL dereference in x25_recvmsg
Date: Wed, 02 Nov 2011 03:21:28 +0100 [thread overview]
Message-ID: <1320200488.4728.29.camel@edumazet-laptop> (raw)
In-Reply-To: <1320200358.4728.28.camel@edumazet-laptop>
Le mercredi 02 novembre 2011 à 03:19 +0100, Eric Dumazet a écrit :
> Le mardi 01 novembre 2011 à 22:15 -0400, Dave Jones a écrit :
> > On Wed, Nov 02, 2011 at 03:10:45AM +0100, Eric Dumazet wrote:
> > > Le mardi 01 novembre 2011 à 21:53 -0400, Dave Jones a écrit :
> > > > commit cb101ed2 in 3.0 introduced a bug in x25_recvmsg()
> > > > When passed bogus junk from userspace, x25->neighbour can be NULL,
> > > > as shown in this oops..
> > > >
> > >
> > > Your patch seems fine but :
> > >
> > > Are you sure this bug is not present on previous kernels ?
> > >
> > > It seems we had prior to this commit :
> > >
> > > skb_pull(skb, x25->neighbour->extended ?
> > > X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
> >
> > It might have been possible with a specifically crafted set of arguments.
> >
> > It never showed up in testing before now, probably because we were
> > returning from the function before we got to that skb_pull
> > via all the other tests that get performed.
> >
>
> neighbour is not an x25_recvmsg() argument, but related to x25 socket
> state.
>
> Maybe your tests dont try to use x25_recvmsg() while socket has no
> neighbour...
>
> This bug was there before the cb101ed2 commit.
>
Ah ok, I see now, we exited early because of
if (sk->sk_state != TCP_ESTABLISHED)
goto out;
So yes, commit cb101ed2 is the bug origin, sorry for the noise.
next prev parent reply other threads:[~2011-11-02 2:21 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-02 1:53 Fix NULL dereference in x25_recvmsg Dave Jones
2011-11-02 2:10 ` Eric Dumazet
2011-11-02 2:15 ` Dave Jones
2011-11-02 2:19 ` Eric Dumazet
2011-11-02 2:21 ` Eric Dumazet [this message]
2011-11-02 2:16 ` Eric Dumazet
2011-11-02 2:26 ` [v2] " Dave Jones
2011-11-02 2:30 ` Eric Dumazet
2011-11-02 4:50 ` David Miller
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