[PATCH nf] netfilter: nfnetlink_cttimeout: nf_proto_net must be first member of netns_proto_gre

[Florian Westphal]

Can't move timeouts around, it appears conntrack sysctl unregister
assumes net_generic() returns nf_proto_net, so we get crash.

Expose layout of netns_proto_gre instead.

Reported-by: kernel test robot <l...@intel.com>
Fixes: 991acf532b  netfilter: nfnetlink_cttimeout: fetch timeouts for udplite 
and gre, too
Signed-off-by: Florian Westphal <f...@strlen.de>
---
 include/linux/netfilter/nf_conntrack_proto_gre.h | 13 +++++++++++++
 net/netfilter/nf_conntrack_proto_gre.c           | 14 +-------------
 net/netfilter/nfnetlink_cttimeout.c              |  8 ++++++--
 3 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/include/linux/netfilter/nf_conntrack_proto_gre.h 
b/include/linux/netfilter/nf_conntrack_proto_gre.h
index b8d95564bd53..14edb795ab43 100644
--- a/include/linux/netfilter/nf_conntrack_proto_gre.h
+++ b/include/linux/netfilter/nf_conntrack_proto_gre.h
@@ -21,6 +21,19 @@ struct nf_ct_gre_keymap {
        struct nf_conntrack_tuple tuple;
 };
 
+enum grep_conntrack {
+       GRE_CT_UNREPLIED,
+       GRE_CT_REPLIED,
+       GRE_CT_MAX
+};
+
+struct netns_proto_gre {
+       struct nf_proto_net     nf;
+       rwlock_t                keymap_lock;
+       struct list_head        keymap_list;
+       unsigned int            gre_timeouts[GRE_CT_MAX];
+};
+
 /* add new tuple->key_reply pair to keymap */
 int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
                         struct nf_conntrack_tuple *t);
diff --git a/net/netfilter/nf_conntrack_proto_gre.c 
b/net/netfilter/nf_conntrack_proto_gre.c
index dd8db7fbc437..2a5e56c6d8d9 100644
--- a/net/netfilter/nf_conntrack_proto_gre.c
+++ b/net/netfilter/nf_conntrack_proto_gre.c
@@ -43,24 +43,12 @@
 #include <linux/netfilter/nf_conntrack_proto_gre.h>
 #include <linux/netfilter/nf_conntrack_pptp.h>
 
-enum grep_conntrack {
-       GRE_CT_UNREPLIED,
-       GRE_CT_REPLIED,
-       GRE_CT_MAX
-};
-
 static const unsigned int gre_timeouts[GRE_CT_MAX] = {
        [GRE_CT_UNREPLIED]      = 30*HZ,
        [GRE_CT_REPLIED]        = 180*HZ,
 };
 
 static unsigned int proto_gre_net_id __read_mostly;
-struct netns_proto_gre {
-       unsigned int            gre_timeouts[GRE_CT_MAX];
-       struct nf_proto_net     nf;
-       rwlock_t                keymap_lock;
-       struct list_head        keymap_list;
-};
 
 static inline struct netns_proto_gre *gre_pernet(struct net *net)
 {
@@ -402,7 +390,7 @@ static int __init nf_ct_proto_gre_init(void)
 {
        int ret;
 
-       BUILD_BUG_ON(offsetof(struct netns_proto_gre, gre_timeouts));
+       BUILD_BUG_ON(offsetof(struct netns_proto_gre, nf) != 0);
 
        ret = register_pernet_subsys(&proto_gre_net_ops);
        if (ret < 0)
diff --git a/net/netfilter/nfnetlink_cttimeout.c 
b/net/netfilter/nfnetlink_cttimeout.c
index 1643faa35f56..109b0d27345a 100644
--- a/net/netfilter/nfnetlink_cttimeout.c
+++ b/net/netfilter/nfnetlink_cttimeout.c
@@ -474,8 +474,12 @@ static int cttimeout_default_get(struct net *net, struct 
sock *ctnl,
                break;
        case IPPROTO_GRE:
 #ifdef CONFIG_NF_CT_PROTO_GRE
-               if (l4proto->net_id)
-                       timeouts = net_generic(net, *l4proto->net_id);
+               if (l4proto->net_id) {
+                       struct netns_proto_gre *net_gre;
+
+                       net_gre = net_generic(net, *l4proto->net_id);
+                       timeouts = net_gre->gre_timeouts;
+               }
 #endif
                break;
        case 255:
-- 
2.18.1