| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.14 114/126] ipv6: defrag: drop non-last frags smaller than min mtu | Date | Tue, 18 Sep 2018 00:42:42 +0200 |
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4.14-stable review patch. If anyone has any objections, please let me know.
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From: Florian Westphal <fw@strlen.de>
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 <posk@google.com> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net> (cherry picked from commit 0ed4229b08c13c84a3c301a08defdc9e7f4467e6) Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv6/netfilter/nf_conntrack_reasm.c | 4 ++++ net/ipv6/reassembly.c | 4 ++++ 2 files changed, 8 insertions(+)
--- 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, 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); --- a/net/ipv6/reassembly.c +++ b/net/ipv6/reassembly.c @@ -522,6 +522,10 @@ static int ipv6_frag_rcv(struct sk_buff 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) {
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