netfilter: ctnetlink: don't permit ct creation with random tuple

Userspace can cause kernel panic by not specifying orig/reply
tuple: kernel will create a tuple with random stack values.

Problem is that tuple.dst.dir will be random, too, which
causes nf_ct_tuplehash_to_ctrack() to return garbage.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@gnumonks.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 627b0e50b238..a081915e0531 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1705,6 +1705,9 @@ ctnetlink_new_conntrack(struct sock *ctnl, struct sk_buff *skb,
                 if (nlh->nlmsg_flags & NLM_F_CREATE) {
                         enum ip_conntrack_events events;
 
+                        if (!cda[CTA_TUPLE_ORIG] || !cda[CTA_TUPLE_REPLY])
+                                return -EINVAL;
+
                         ct = ctnetlink_create_conntrack(net, zone, cda, &otuple,
                                                         &rtuple, u3);
                         if (IS_ERR(ct))