netfilter: limit the length of the helper name

This is necessary in order to have an upper bound for Netlink
message calculation, which is not a problem at all, as there
are no helpers with a longer name.

Signed-off-by: Holger Eitzenberger <holger@eitzenberger.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>

2 files changed, 3 insertions, 0 deletions

diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
index 66d65a7caa39..ee2a4b369a04 100644
--- a/include/net/netfilter/nf_conntrack_helper.h
+++ b/include/net/netfilter/nf_conntrack_helper.h
@@ -14,6 +14,8 @@
 
 struct module;
 
+#define NF_CT_HELPER_NAME_LEN   16
+
 struct nf_conntrack_helper
 {
         struct hlist_node hnode;        /* Internal use. */
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index a51bdac9f3a0..805cfdd42303 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -142,6 +142,7 @@ int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
 
         BUG_ON(me->expect_policy == NULL);
         BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
+        BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
 
         mutex_lock(&nf_ct_helper_mutex);
         hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);