netfilter: nf_conntrack_gre: more locking around keymap list

gre_keymap_list should be protected in all places.
(unless I'm misreading something)

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/net/netfilter/nf_conntrack_proto_gre.c b/net/netfilter/nf_conntrack_proto_gre.c
index 654a4f7f12c6..b308bb4c12b9 100644
--- a/net/netfilter/nf_conntrack_proto_gre.c
+++ b/net/netfilter/nf_conntrack_proto_gre.c
@@ -97,10 +97,14 @@ int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
         kmp = &help->help.ct_pptp_info.keymap[dir];
         if (*kmp) {
                 /* check whether it's a retransmission */
+                read_lock_bh(&nf_ct_gre_lock);
                 list_for_each_entry(km, &gre_keymap_list, list) {
-                        if (gre_key_cmpfn(km, t) && km == *kmp)
+                        if (gre_key_cmpfn(km, t) && km == *kmp) {
+                                read_unlock_bh(&nf_ct_gre_lock);
                                 return 0;
+                        }
                 }
+                read_unlock_bh(&nf_ct_gre_lock);
                 pr_debug("trying to override keymap_%s for ct %p\n",
                          dir == IP_CT_DIR_REPLY ? "reply" : "orig", ct);
                 return -EEXIST;