4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Florian Westphal <fw@xxxxxxxxx>
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 <posk@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Mao Wenan <maowenan@xxxxxxxxxx>
[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 <ben.hutchings@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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) {
