From: Xin Long <lucien.xin@gmail.com>
To: Florian Westphal <fw@strlen.de>
Cc: network dev <netdev@vger.kernel.org>, davem <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>,
Steffen Klassert <steffen.klassert@secunet.com>
Subject: Re: [PATCH net] udp: fix a skb extensions leak
Date: Tue, 31 Mar 2020 00:14:46 +0800 [thread overview]
Message-ID: <CADvbK_c9H4MtiQ1bMD3-jXUM_8LRxVC-KaHKyX1r7bhKuxwimg@mail.gmail.com> (raw)
In-Reply-To: <20200330132759.GA31510@strlen.de>
On Mon, Mar 30, 2020 at 9:28 PM Florian Westphal <fw@strlen.de> wrote:
>
> Xin Long <lucien.xin@gmail.com> wrote:
> > On udp rx path udp_rcv_segment() may do segment where the frag skbs
> > will get the header copied from the head skb in skb_segment_list()
> > by calling __copy_skb_header(), which could overwrite the frag skbs'
> > extensions by __skb_ext_copy() and cause a leak.
> >
> > This issue was found after loading esp_offload where a sec path ext
> > is set in the skb.
> >
> > On udp tx gso path, it works well as the frag skbs' extensions are
> > not set. So this issue should be fixed on udp's rx path only and
> > release the frag skbs' extensions before going to do segment.
> > Reported-by: Xiumei Mu <xmu@redhat.com>
> > Fixes: cf329aa42b66 ("udp: cope with UDP GRO packet misdirection")
>
> Hmm, I suspect this bug came in via
> 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596 , net: Support GRO/GSO fraglist chaining.
>
> I suspect correct fix is:
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 621b4479fee1..7e29590482ce 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -3668,6 +3668,7 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb,
>
> skb_push(nskb, -skb_network_offset(nskb) + offset);
>
> + skb_release_head_state(nskb);
> __copy_skb_header(nskb, skb);
>
> skb_headers_offset_update(nskb, skb_headroom(nskb) - skb_headroom(skb));
>
> AFAICS we not only leak reference of extensions, but also skb->dst and skb->_nfct.
Works for this issue.
Tested-by: Xin Long <lucien.xin@gmail.com>
prev parent reply other threads:[~2020-03-30 16:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-26 9:06 [PATCH net] udp: fix a skb extensions leak Xin Long
2020-03-26 9:28 ` Xin Long
2020-03-30 4:54 ` David Miller
2020-03-30 8:29 ` Steffen Klassert
2020-03-30 16:13 ` Xin Long
2020-03-30 16:13 ` Florian Westphal
2020-03-30 13:27 ` Florian Westphal
2020-03-30 13:45 ` Steffen Klassert
2020-03-30 14:11 ` Florian Westphal
2020-03-30 14:39 ` Steffen Klassert
2020-03-30 16:14 ` Xin Long [this message]
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