4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Florian Westphal <[email protected]> commit 0ed4229b08c13c84a3c301a08defdc9e7f4467e6 upstream. 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 <[email protected]> Cc: Eric Dumazet <[email protected]> Signed-off-by: Florian Westphal <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Mao Wenan <[email protected]> [bwh: Backported to 4.4: In nf_ct_frag6_gather() use clone instead of skb, and goto ret_orig in case of error] Signed-off-by: Ben Hutchings <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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 @@ -574,6 +574,10 @@ struct sk_buff *nf_ct_frag6_gather(struc hdr = ipv6_hdr(clone); fhdr = (struct frag_hdr *)skb_transport_header(clone); + if (clone->len - skb_network_offset(clone) < IPV6_MIN_MTU && + fhdr->frag_off & htons(IP6_MF)) + goto ret_orig; + 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 @@ -515,6 +515,10 @@ 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) {
