[PATCH 3.16.y-ckt 122/129] netfilter: nf_tables: check for overflow of rule dlen field

[Luis Henriques]

3.16.7-ckt12 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Patrick McHardy <kaber at trash.net>

commit 9889840f5988ecfd43b00c9abb83c1804e21406b upstream.

Check that the space required for the expressions doesn't exceed the
size of the dlen field, which would lead to the iterators crashing.

Signed-off-by: Patrick McHardy <kaber at trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/netfilter/nf_tables_api.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index e8624c751ec6..41abb8281a4c 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1794,6 +1794,10 @@ static int nf_tables_newrule(struct sock *nlsk, struct sk_buff *skb,
 			n++;
 		}
 	}
+	/* Check for overflow of dlen field */
+	err = -EFBIG;
+	if (size >= 1 << 12)
+		goto err1;
 
 	if (nla[NFTA_RULE_USERDATA])
 		ulen = nla_len(nla[NFTA_RULE_USERDATA]);