From: Florian Westphal <fw@strlen.de>
To: Eric Dumazet <edumazet@google.com>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>,
Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
Florian Westphal <fw@strlen.de>,
netfilter-devel@vger.kernel.org, netdev <netdev@vger.kernel.org>,
Eric Dumazet <eric.dumazet@gmail.com>,
syzbot <syzkaller@googlegroups.com>
Subject: Re: [PATCH netfilter] netfilter: bridge: make sure to pull arp header in br_nf_forward_arp()
Date: Mon, 9 Dec 2019 00:31:55 +0100 [thread overview]
Message-ID: <20191208233155.GH795@breakpoint.cc> (raw)
In-Reply-To: <20191207224339.91704-1-edumazet@google.com>
Eric Dumazet <edumazet@google.com> wrote:
> syzbot is kind enough to remind us we need to call skb_may_pull()
[..]
> Fixes: c4e70a87d975 ("netfilter: bridge: rename br_netfilter.c to br_netfilter_hooks.c")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: syzbot <syzkaller@googlegroups.com>
> ---
>
> Note: Fixes: tag does not point to real bug origin, but is old enough
> to cover all stable versions.
Indeed, looks like a day0 bug. We don't have this problem for ipv4/6
because the prerouting hook does pskb_may_pull() as part of ipv4/6
header checks. Arp doesn't have anything like it.
> nf_bridge_pull_encap_header(skb);
> }
>
> + if (unlikely(!pskb_may_pull(skb, sizeof(struct arphdr))))
> + return NF_DROP;
> +
> if (arp_hdr(skb)->ar_pln != 4) {
Thats indeed the only location where we call NFPROTO_ARP hooks,
so this looks like the proper fix/location.
Thanks Eric!
Reviewed-by: Florian Westphal <fw@strlen.de>
next prev parent reply other threads:[~2019-12-08 23:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-07 22:43 [PATCH netfilter] netfilter: bridge: make sure to pull arp header in br_nf_forward_arp() Eric Dumazet
2019-12-08 23:31 ` Florian Westphal [this message]
2019-12-09 11:58 ` Pablo Neira Ayuso
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