From: Cong Wang <xiyou.wangcong@gmail.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>,
"David S. Miller" <davem@davemloft.net>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
James Morris <jmorris@namei.org>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
Patrick McHardy <kaber@trash.net>,
netdev <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Eric Dumazet <edumazet@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Kostya Serebryany <kcc@google.com>,
syzkaller <syzkaller@googlegroups.com>
Subject: Re: net/ipv4: use-after-free in ipv4_datagram_support_cmsg
Date: Wed, 12 Apr 2017 13:07:59 -0700 [thread overview]
Message-ID: <CAM_iQpVVc1ev8juG8=dQ0wu8c_RoJ8HfDUewRc1AempvV=85kw@mail.gmail.com> (raw)
In-Reply-To: <CAF=yD-++XtWeaVmdhnrwiYLOG84JTMEuZr9mxyTRnde8vE7AFQ@mail.gmail.com>
On Wed, Apr 12, 2017 at 8:39 AM, Willem de Bruijn
<willemdebruijn.kernel@gmail.com> wrote:
> ===================
>> BUG: KASAN: use-after-free in ipv4_datagram_support_cmsg
>> net/ipv4/ip_sockglue.c:500 [inline] at addr ffff880059be0128
>
> Thanks for the report. This is accessing skb->dev from within recvmsg() at line
>
> info->ipi_ifindex = skb->dev->ifindex;
>
> Introduced in 829ae9d61165 ("net-timestamp: allow reading recv cmsg on
> errqueue with origin tstamp"). At this time the device may indeed have
> gone away. I'm having a look at a way to read this in the receive BH
> and store the ifindex.
Why not use skb_iif?
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index ebd953b..a2aef45 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -497,7 +497,7 @@ static bool ipv4_datagram_support_cmsg(const
struct sock *sk,
info = PKTINFO_SKB_CB(skb);
info->ipi_spec_dst.s_addr = ip_hdr(skb)->saddr;
- info->ipi_ifindex = skb->dev->ifindex;
+ info->ipi_ifindex = skb->skb_iif;
return true;
}
next prev parent reply other threads:[~2017-04-12 20:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-12 14:44 net/ipv4: use-after-free in ipv4_datagram_support_cmsg Andrey Konovalov
2017-04-12 15:39 ` Willem de Bruijn
2017-04-12 20:07 ` Cong Wang [this message]
2017-04-12 20:47 ` Eric Dumazet
2017-04-12 22:25 ` Willem de Bruijn
2017-04-12 23:26 ` Willem de Bruijn
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