From: Ben Hutchings <ben@decadent.org.uk>
To: Eric Dumazet <eric.dumazet@gmail.com>,
Anarcheuz Fritz <anarcheuz@gmail.com>
Cc: davem@davemloft.net, security@kernel.org, netdev@vger.kernel.org
Subject: Re: PROBLEM: null-ptr deref in ip_options_echo may lead to denial of service
Date: Tue, 21 Mar 2017 00:36:01 +0000 [thread overview]
Message-ID: <1490056561.4770.7.camel@decadent.org.uk> (raw)
In-Reply-To: <1490056423.4770.6.camel@decadent.org.uk>
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On Tue, 2017-03-21 at 00:33 +0000, Ben Hutchings wrote:
> On Sun, 2017-03-19 at 22:25 -0700, Eric Dumazet wrote:
> > On Mon, 2017-03-20 at 12:59 +0800, Anarcheuz Fritz wrote:
> > > Hi David,
> > >
> > >
> > > While working on some legacy kernel I stumbled upon a null-ptr deref in
> > > ip_options_echo. The bug has been verified on the latest version
> > > 3.2.87 from the supported long-term branch.
> > >
> >
> > Fixed in commit 34b2cef20f19c87999fff3da4071e66937db9644
> > ("ipv4: keep skb->dst around in presence of IP options")
> >
> > For 3.2, since d826eb14ecef was not backported, following patch should
> > do it.
> >
> > (Bug origin was f84af32cbca70 ("net: ip_queue_rcv_skb() helper"))
>
> I see, I thought the vulnerability was introduced by d826eb14ecef.
>
> > diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> > index b3648bbef0da..a6e1eeb02267 100644
> > --- a/net/ipv4/ip_sockglue.c
> > +++ b/net/ipv4/ip_sockglue.c
> > @@ -1009,7 +1009,8 @@ e_inval:
> > */
> > int ip_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> > {
> > - if (!(inet_sk(sk)->cmsg_flags & IP_CMSG_PKTINFO))
> > + if (!(inet_sk(sk)->cmsg_flags & IP_CMSG_PKTINFO) &&
> > + !IPCB(skb)->opt.optlen)
> > skb_dst_drop(skb);
> > return sock_queue_rcv_skb(sk, skb);
> > }
>
> Thanks to both of you; I'll queue this up for 3.2.
Actually, could I have a Signed-off-by for this, Eric?
Ben.
--
Ben Hutchings
Power corrupts. Absolute power is kind of neat.
- John Lehman, Secretary of the US Navy
1981-1987
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next prev parent reply other threads:[~2017-03-21 0:36 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-20 4:59 PROBLEM: null-ptr deref in ip_options_echo may lead to denial of service Anarcheuz Fritz
2017-03-20 5:25 ` Eric Dumazet
2017-03-21 0:33 ` Ben Hutchings
2017-03-21 0:36 ` Ben Hutchings [this message]
2017-03-21 4:23 ` [PATCH net-stable] ipv4: keep skb->dst around in presence of IP options Eric Dumazet
2017-03-21 11:25 ` Ben Hutchings
2017-03-21 4:24 ` PROBLEM: null-ptr deref in ip_options_echo may lead to denial of service Eric Dumazet
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