From 0ed4229b08c13c84a3c301a08defdc9e7f4467e6 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Fri, 3 Aug 2018 02:22:20 +0200 Subject: ipv6: defrag: drop non-last frags smaller than min mtu 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 --- net/ipv6/reassembly.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'net/ipv6/reassembly.c') diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c index b4e558ab39fa..5c5b4f79296e 100644 --- a/net/ipv6/reassembly.c +++ b/net/ipv6/reassembly.c @@ -456,6 +456,10 @@ 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) { -- cgit v1.2.3-55-g7522