netfilter: nf_tables: check for overflow of rule dlen field

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@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 6fb532bf0fdb522a609d6b9182593344ec48f0a5..7baafd5ab52093bf2148076cbba320e17f6c7e2a 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1968,6 +1968,10 @@ 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]);