From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Fainelli Subject: [PATCH stable 4.9 22/29] ipv6: defrag: drop non-last frags smaller than min mtu Date: Tue, 9 Oct 2018 15:49:17 -0700 Message-ID: <20181009224924.30151-23-f.fainelli@gmail.com> References: <20181009224924.30151-1-f.fainelli@gmail.com> Cc: davem@davemloft.net, gregkh@linuxfoundation.org, stable@vger.kernel.org, edumazet@google.com, sthemmin@microsoft.com, Florian Westphal , Peter Oskolkov To: netdev@vger.kernel.org Return-path: Received: from mail-pf1-f195.google.com ([209.85.210.195]:35531 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727804AbeJJGJ2 (ORCPT ); Wed, 10 Oct 2018 02:09:28 -0400 In-Reply-To: <20181009224924.30151-1-f.fainelli@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Florian Westphal don't bother with pathological cases, they only waste cycles. IPv6 requires a minimum MTU of 1280 so we should never see fragments smaller than this (except last frag). v3: don't use awkward "-offset + len" v2: drop IPv4 part, which added same check w. IPV4_MIN_MTU (68). There were concerns that there could be even smaller frags generated by intermediate nodes, e.g. on radio networks. Cc: Peter Oskolkov Cc: Eric Dumazet Signed-off-by: Florian Westphal Signed-off-by: David S. Miller (cherry picked from commit 0ed4229b08c13c84a3c301a08defdc9e7f4467e6) --- net/ipv6/netfilter/nf_conntrack_reasm.c | 4 ++++ net/ipv6/reassembly.c | 4 ++++ 2 files changed, 8 insertions(+) diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c index ff49d1f2c8cb..b81541701346 100644 --- a/net/ipv6/netfilter/nf_conntrack_reasm.c +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c @@ -564,6 +564,10 @@ int nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 user) hdr = ipv6_hdr(skb); fhdr = (struct frag_hdr *)skb_transport_header(skb); + if (skb->len - skb_network_offset(skb) < IPV6_MIN_MTU && + fhdr->frag_off & htons(IP6_MF)) + return -EINVAL; + skb_orphan(skb); fq = fq_find(net, fhdr->identification, user, hdr, skb->dev ? skb->dev->ifindex : 0); diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c index dbe726c9a2ae..78656bbe50e7 100644 --- a/net/ipv6/reassembly.c +++ b/net/ipv6/reassembly.c @@ -516,6 +516,10 @@ static int ipv6_frag_rcv(struct sk_buff *skb) return 1; } + if (skb->len - skb_network_offset(skb) < IPV6_MIN_MTU && + fhdr->frag_off & htons(IP6_MF)) + goto fail_hdr; + iif = skb->dev ? skb->dev->ifindex : 0; fq = fq_find(net, fhdr->identification, hdr, iif); if (fq) { -- 2.17.1