From: Florian Westphal <fw@strlen.de>
To: "Maciej Żenczykowski" <zenczykowski@gmail.com>
Cc: Lorenzo Colitti <lorenzo@google.com>,
Eric Dumazet <edumazet@google.com>,
Florian Westphal <fw@strlen.de>,
Linux NetDev <netdev@vger.kernel.org>,
Maciej Zenczykowski <maze@google.com>
Subject: Re: crash in xt_policy due to skb_dst_drop() in nf_ct_frag6_gather()
Date: Tue, 16 Oct 2018 10:11:20 +0200 [thread overview]
Message-ID: <20181016081120.umbe3kz2vi4jfgks@breakpoint.cc> (raw)
In-Reply-To: <CANP3RGeX5=c=Lb+Pkg89zD7zQ_Z1T8oPJRCkorNCdghmofYXxg@mail.gmail.com>
Maciej Żenczykowski <zenczykowski@gmail.com> wrote:
I am currently travelling and not able to investigate
until next week.
> commit ad8b1ffc3efae2f65080bdb11145c87d299b8f9a
> Author: Florian Westphal <fw@strlen.de>
> netfilter: ipv6: nf_defrag: drop skb dst before queueing
>
> +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
> @@ -618,6 +618,8 @@ int nf_ct_frag6_gather(struct net *net, struct
> sk_buff *skb, u32 user)
> fq->q.meat == fq->q.len &&
> nf_ct_frag6_reasm(fq, skb, dev))
> ret = 0;
> + else
> + skb_dst_drop(skb);
This is only supposed to drop dst of skbs that are enqueued,
i.e. frag6_gather returns NF_STOLEN.
In case skb completes the queue, then that skbs dst_entry
is supposed to be kept, so skb_dst() does NOT return NULL.
Its not supposed to be any different than ipv4 defrag.
> const struct dst_entry *dst = skb_dst(skb); // returns NULL
That is not supposed to happen.
next prev parent reply other threads:[~2018-10-16 16:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-16 4:13 crash in xt_policy due to skb_dst_drop() in nf_ct_frag6_gather() Maciej Żenczykowski
2018-10-16 8:11 ` Florian Westphal [this message]
2018-10-16 9:40 ` Maciej Żenczykowski
2018-10-16 9:41 ` Maciej Żenczykowski
2018-10-16 9:49 ` Maciej Żenczykowski
2018-10-23 14:47 ` [PATCH nf] netfilter: ipv6: fix oops when defragmenting locally generated fragments Florian Westphal
2018-10-23 14:54 ` Eric Dumazet
2018-10-23 21:04 ` Maciej Żenczykowski
2018-10-23 22:04 ` Florian Westphal
2018-10-25 8:18 ` Pablo Neira Ayuso
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