From: Florian Westphal Date: Thu, 13 Sep 2018 14:58:55 +0000 (-0700) Subject: ipv6: defrag: drop non-last frags smaller than min mtu X-Git-Tag: v4.14.71~13 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=5123ffdad65954b3c308e055b388db08987a13ff;p=users%2Fjedix%2Flinux-maple.git 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 (cherry picked from commit 0ed4229b08c13c84a3c301a08defdc9e7f4467e6) Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c index a1dc0d6a59498..1d2f07cde01a5 100644 --- a/net/ipv6/netfilter/nf_conntrack_reasm.c +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c @@ -565,6 +565,10 @@ 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 e1c5fa5e3873f..afaad60dc2ac1 100644 --- a/net/ipv6/reassembly.c +++ b/net/ipv6/reassembly.c @@ -522,6 +522,10 @@ 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) {